JUDGMENT R.N. Sahay, J. The pertinent question for decision in this appeal is as to whether the defendant in a suit for Specific Performance of an agreement for reconveyance of a house can be allowed to resist the suit on the plea of existence of separate oral agreement in derogation of the written agreement for sale and whether he can be allowed to lead evidence to show that the agreement for sale was never intended to be acted upon, in view of the subsequent oral agreement. 2. The plaintiff-respondent instituted a suit for decree of Specific Performance of agreement of sale of residential house situated in the town of Giridih. The plaintiff in the alternative prayed for decree of damages. 3. It is not in dispute that the house involved in the litigation belonged exclusively to the plaintiff-respondent. She sold the house to the appellant by means of a registered deed en 5. 6.1971 for a consideration of Rs. 2250/- The same day, the appellant executed a deed of agreement whereby he agreed to reconvey this property to the respondent for the same sum of Rs. 2250/- and to execute a sale deed in respect of the building in favour of the respondent if the latter paid the sum of Rs. 2250/- to the appellant within a period of 5 years from the date of the agreement. On the following day i.e. 6.6.1971, the husband of the respondent executed a deed in favour of the appellant whereby he acknowledged to have taken the building en rent from the appellant from 6.6.1971 on a monthly rent of Rs. 45/-. Respondents husband has all through been in possession of the building in which he and the members of his family have all along been living. 4. The case of the plaintiff-respondent was that she sold the house to the appellant but she never parted with the actual physical possession of the he use. She gave only a symbolic possession of the house to the appellant but continued to be in actual physical possession of the house. She was all along ready and willing for the recanveyance of the building from the appellant as per the agreement executed by the appellant an 5.6.1971 an payment of a sum of Rs. 2250/-. She gave only a symbolic possession of the house to the appellant but continued to be in actual physical possession of the house. She was all along ready and willing for the recanveyance of the building from the appellant as per the agreement executed by the appellant an 5.6.1971 an payment of a sum of Rs. 2250/-. In April and May, 1976 she requested the appellant through her husband to reconvey the property by executing a deed of sale in her favour, as agreed upon by the deed of agreement. The appellant evaded executing sale deed an one pretext or other. The plaintiff then sent a notice through lawyer calling upon the appellant to execute the sale deed. There was no response from the appellant hence the suit was instituted. 5. According to the defendant-appellant, on the day the respondent executed the sale deed in his favour she gave possession of the house to him. On the following day i.e. 6.6.1971 the respondent and her husband requested him to let-out the house to the respondent's husband on a monthly rental of Rs. 45/- and in lieu thereof, the respondent agreed to forego her right under the deed of agreement executed by the appellant to re-convey the house on the defendant-respondent. The appellant accepted the proposal made by the respondent and her husband and let-out the house to the respondents' husband on a monthly rental of Rs. 45/-. The respondent's husband executed a deed acknowledging to have taken the house on payment of monthly rental of Rs. 45/- and as had been offered and suggested by the defendant and her husband, the respondent handed back the deed of agreement executed by the appellant in favour of the respondent whereby the appellant had agreed and undertaken to reconvey the house to the respondent. The appellant denied that the respondent had no occasion to request him to re-convey the property and execute the sale deed. Thus the case of the appellant is that the respondent handed back to him the agreement for sale executed in her favour as a consideration for let-out the building to the husband respondent and so he stands discharged of his liability to re-convey the building to the respondent and to execute the sale deed in her favour. 6. Thus the case of the appellant is that the respondent handed back to him the agreement for sale executed in her favour as a consideration for let-out the building to the husband respondent and so he stands discharged of his liability to re-convey the building to the respondent and to execute the sale deed in her favour. 6. The trial court, after considering the evidence and the contention advanced by the rival parties, held that the defendant having not executed the sale deed in favour of the plaintiff had failed to discharge his obligation. As regards the claim of the appellant that the plaintiff and her husband had orally agreed not to claim re-conveyance, the trial court held even if there was any such agreement it was required to be registered and hence the evidence of the appellant on this score was liable to be rejected. 7. The learned appellate court has considered the question of admissibility of the subsequent oral agreement rescinding the agreement by which the appellant had agreed to reconvey the property and has held that it was impermissible in view of proviso 4 to Section 92 of the Indian Evidence Act. The reasoning of the appellate court is as follows : "Since no presumption that the appellant stands discharged of his liability to resell the property to the respondent can or ought to be made the onus remains on the appellant to prove that he has been discharged of his obligation to executes sale deed in favour of the respondent. The appellant admits that the deed of agreement executed by him to re-sell the property to the respondent was registered. And therefore any subsequent agreement rescinding this contract could have been made only by a registered instrument. Since the deed of agreement was a registered instrument the reception of oral evidence of an agreement rescinding the agreement to sell is barred by proviso 4 to Section 92 of Evidence Act. It was because of this reason that the appellant was not allowed to prove subsequent oral agreement to rescind the agreement for re-sale of the house. The learned trial court had prohibited the appellant from adducing oral evidence of subsequent agreement by a discussed order in writing. The appellant did not move any higher court against this order. It was because of this reason that the appellant was not allowed to prove subsequent oral agreement to rescind the agreement for re-sale of the house. The learned trial court had prohibited the appellant from adducing oral evidence of subsequent agreement by a discussed order in writing. The appellant did not move any higher court against this order. And in my opinion the learned trial court rightly disallowed the appellant to adduce oral evidence of the fact that the respondent had agreed to forego her right to the reconveyance of the property as a consideration for getting the house on rent. And for this reason there is no evidence on the record from the side of the appellant that his agreement to re-sale the property to the respondent was received as there is absolutely no evidence from the side of the appellant of the fact that he stands discharged of his obligation to re-sell the house". 8. Shri N.K. Prasad the learned counsel for the appellant has seriously assailed the decision of the appellate court that in the facts and circumstances of the case, the defendant appellant was debarred from leading evidence that there was subsequent oral agreement rescinding the agreement by which the appellant agreed to re-convey the property if the plaintiff agreed to take back the house within 5 years of the execution of the sale deed. 9. Shri V. Shivnath, the learned counsel for the plaintiff-respondent, on the other hand, argued that the conclusion of both the courts on this aspect was correct and further even if there was oral evidence it could not be acted upon by registered (sic). Even if, there was such an agreement as put forward by the defendant, it could not be acted upon unless there was registered agreement. 10. Shri Prasad, in support of his submission placed reliance on the case of Smt. Gangabai vs. Smt. Chhabubai reported in A.I.R. 1982 S.C. 20. In the aforesaid case it was held by the Hon'ble Supreme Court that sub-section 1 of section 92 is not attracted when the case of a party is that the transactions recorded in the document was never intended to be acted upon at all between the parties and the document is a sham. In the aforesaid case it was held by the Hon'ble Supreme Court that sub-section 1 of section 92 is not attracted when the case of a party is that the transactions recorded in the document was never intended to be acted upon at all between the parties and the document is a sham. Such a question arises when the parties asserts that there was a different transaction altogether and what is recorded in the document was never intended to be of no consequence whatever. For that purpose oral evidence is admissible to show that the document executed was never intended to operate as an agreement, but that some other agreement altogether, not recorded in the document, was never entered into between the parties. In my opinion, however, the decision in Smt. Gangabai case (supra) haw no application to the present case because hero we are concerned to proviso 4 to Section 92 of the Evidence Act and not proviso (1). 11. Section 92 of the Indian Evidence Act reads as follows : "When the terms of any such contract, grant of other disposition of property, or any matter required by law to be reduced to the form of a document, have been proved according to the last section, no evidence of any oral agreement or statement shall be admitted as between the parties to any such instrument or their representatives in interest, for the purpose of contracting, varying, adding to, or subtracting from, its terms". 12. Proviso 4 of Section 92 of the Indian Evidence Act reads as follows: "The existence of any distinct subsequent oral agreement to rescind or modify any such contract, grant or disposition of property, may be proved, except in case in which such contract, grant or disposition or property is by law required to be in writing, or has been registered according to the law in force for the time being as to the registration of documents. This proviso deals with three situations viz : (1) Where a transaction has been reduced into writing not because the law requires it to be so done, but by agreement for the convenience of the parties, the parol evidence of any distinct subsequent oral agreement modifying or rescinding it altogether is admissible. This proviso deals with three situations viz : (1) Where a transaction has been reduced into writing not because the law requires it to be so done, but by agreement for the convenience of the parties, the parol evidence of any distinct subsequent oral agreement modifying or rescinding it altogether is admissible. (2) But where a matter has been reduced into writing because the law requires it to be in writing for its validity, no parol evidence can be given of any subsequent agreement rescinding or modifying it. It can only be waived rescinded, modified or altered by another written instrument of equally solemn character. (3) The rule applied to all registered instruments, whether or not registration is compulsory under the law. So, when a writing embodying a contract, grant has been registered, parol evidence of any subsequent agreement modifying or rescinding the registered instrument is not admissible. It must be modified, altered or waived by another registered instrument. The rule laid down in this proviso is based upon the case of Goss v. Nugent 2 B.’ Ad. 58, where LORD DENMAN said: “By the general rules of the common law, if there be a contract which has been reduced into writing, verbal evidence is not allowed to be given of what passed between the parties either before the written instrument was made, or during the time that it was in a state of preparation, so as to add to or substract from, or in any manner to vary or qualify, the written contract; but after the agreement has been reduced into writing, it is competent to the parties, at any time before breach of it, by a new Contract not in writing, either altogether to waive, dissolve, or annul the former agreements, or in any manner to add to, or substract from, or vary or qualify the terms of it, and thus to make a new contract; which is to be proved, partly by the written agreement and partly by the subsequent verbal terms, engrafted upon what will be thus left of the written agreement. The problem poled in this appeal is no doubt a vexed one. The problem poled in this appeal is no doubt a vexed one. As Wigmore has observed in his celebrated treatise of law of Evidence "the application of this principle varies in practice according to the nature of the particular legal right and the actual operation of the Rule should be in almost all cases left to the trial Judge's determination” In Dominion of India V. Ram Rakha Mall & Sons, A.I.R. 1957 Punjab 141 it has been observed by Bishan Narain, J: “It is held that this vexed question relating to precise scope of S. 92 on contemporaneous or subsequent agreement evidenced by oral assurances or by conduct of the parties will soon be decided authoritatively by their Lordships of the Supreme Court" 18. In the case at hand the appellant had executed a registered agreement of re-conveyance of the suit house, although such agreement need not be in writing. In K. Hutahi Gowder v. H. Bheema Gowder, A.I.R. 1960 Md. 33 (D.B.) it has been held by the Madras High Court that an agreement to convey though reduced in writing, is not required by law to be in writing so an unregistered agreement can be modified by an oral agreement entered into by the parties. 14. In Ramchandra San V. Kailash Chandra Patra, A.I.R. 1931 Cal. 667 (D.B.) it was held a Solemnama for the discharge or satisfaction of a registered mortgage, not being a document entered into by the parties for the purpose of varying the terms of the mortgage security, is admissible in evidence even without registration". The decision of the Calcutta High Court was based on earlier decision in Mohini Chandra Dey V. Ramdayal Datta, A.I.R. 1926 Cal. : 170. It was further held "there is nothing in law to exclude even oral evidence of discharge or release of a mortgage deed". 1 S. In Durga Pd. Singh v. Rajendra Narayan Bagchi 40 IA 233 (P.C.), it was held by the Privy Council that terms of a registered instrument which was foundation of the claim could not be varied by extraneous evidence. Their Lordships of the Calcutta High Court in Ramchandra Sau's case (supra) held that the Privy Council case was not applicable. Their Lordships further held that : "Here the contract has not been varied, as we have mentioned already, by the solemnama. Their Lordships of the Calcutta High Court in Ramchandra Sau's case (supra) held that the Privy Council case was not applicable. Their Lordships further held that : "Here the contract has not been varied, as we have mentioned already, by the solemnama. It was the discharge of the debt, so far as the mortgage security is concerned that was evidenced by the solemnama. It may also be mentioned that, if there is an arrangement between the parties by an agreement like the one which is before us in the present case, embodied in the compromise, stipulating that the mortgage deed was to be discharged by payment of Rs. 400, it did not require registration for the purpose of using it in evidence" 16. There is another aspect of the matter and that is applicability of doctrine of equitable estoppel in the facts and circumstances of the case. According to the defendant appellant, plaintiff-respondent agreed to forego her right under the deed of re-conveyance if the house was let out to her on rent. The Madhya Pradesh High Court in State Bank of Indore v. M/s Jasroop Baijnath Joint Hindu Family Firm, A.I.R. 1974 M.P. 193 (D.B.) applied the doctrine of equitable estoppel and it was held by Sohani, J. : "On behalf of the respondents, it was contended that it was not open to the executing court to act on the terms of the letter Ex. P-1 in view of the bar imposed by proviso 4 to Section 92 of the Evidence Act, and Sections 49 and 50 of the Registration Act. Now, so far as the contention of the respondents based on applicability of Proviso 4 to Section 92 of the Evidence Act, is concerned, it cannot be sustained in view of the fact that the rule of estoppel must prevail against a pure rule of procedure contained in Section 92 of the Evidence Act. This is not a case where the appellant is seeking to enforce its rights flowing from an unregistered document varying the terms of a registered document. All that the appellant seeks to do is to contend that the respondents are estopped from claiming a refund in the execution proceedings on the ground that there bas been an excess payment received by the appellant under the terms of the compromise dated 17.11.1951. All that the appellant seeks to do is to contend that the respondents are estopped from claiming a refund in the execution proceedings on the ground that there bas been an excess payment received by the appellant under the terms of the compromise dated 17.11.1951. As the respondents, by their own conduct and assurance contained in the letter Ex. P-1, have led that appellant to act in the way it has done, the respondents cannot now be permitted to fall back upon Sec. 92 of the Evidence Act, and thereby escape the consequences of their own action". Their Lordships of Madhya Pradesh High Court relied on the following dictum laid down by Lord Cairns in Hughes v. Metropolitan Railway Co. (1877) 2 App, Cases 439. "It is the first principle upon which all Courts of Equity proceed that if parties who have entered into definite and distinct terms involving certain legal result., certain penalties or legal forfeiture-afterwards by their own act or with their consent enter upon a course of negotiations which has the effect of leading one of the parties to suppose that the strict rights arising under the contract will not be enforced, or will be kept in suspense, or held in abeyance, the person who otherwise might have enforced, or will be kept in suspense, or held in abeyance, the person who otherwise might have enforced these rights will no. be allowed to enforce them where it would be inequitable having regard to the dealings which have thus taken place between the parties". Their Lordships of the Madhya Pradesh High Court further observed : "Based on this principle, the doctrine now appears to be well settled that where one party has by his words or conduct, made to the other a promise or assurance which was intended to affect the legal relation between them and to be acted on accordingly, then, once the other party has taken him at his word and acted on it, the party who gave the promise or assurance cannot afterwards be allowed to revert to the previous legal relationship as if no such promise or assurance had been made by him. He must accept their legal relations subject to the qualification which he himself has so introduced, even though it is not supported in point of law by any consideration, but only by his word. He must accept their legal relations subject to the qualification which he himself has so introduced, even though it is not supported in point of law by any consideration, but only by his word. This principle, enunciated in Central London Property Trust Ltd. Vs. High Trees House Ltd. (1947) 1 KB 130 has been recognised by the Supreme Court in Turner Morrison and Co. Ltd. Vs. Hungerford Investment Trust Ltd., AIR 1972 SC 1311 . In that case the Supreme Court has observed that the rule laid down in those decisions advanced the cause of justice. We have therefore, no hesitation in applying that rule in the circumstances of this case". In A.I.R. 1957 Punjab 141 already referred to it was held : "It may be that the written contract cannot be modified by oral agreement, but it is open to a party by its conduct or by oral assurances to induce the other party into believing that the contract need not be performed in accordance with the written terms of the contract and in such a case it is obvious that it would be most unjust to permit such a party to turn round later on and to rely on the written terms of the contract. Even if the principle of estoppel is not applicable to such a case, the principle applicable to it may be described as principle of "quasi estoppel" as a principle of equity. After all the rules of evidence are meant to advance justice and not to hamper or defeat it." 17. Having regard to discussions above, in my opinion, the appellant was entitled to lead oral evidence of the alleged subsequent agreement that the plaintiff respondent agreed not to enforce the right under reconveyance deed if the house in question was given to her on rent. The courts below were wrong in holding that oral evidence was prohibited under Section 92 (4) of the Evidence Act. The appeal is, therefore, allowed and the judgment and decree of the appellate court is set-aside. As the appellant was not given opportunity to adduce evidence with respect to subsequent agreement, the case is remitted to the appellate court for disposal in accordance with law after giving liberty to the appellant to adduce further evidence. The plaintiff shall be entitled to lead evidence in rebuttal. As the appellant was not given opportunity to adduce evidence with respect to subsequent agreement, the case is remitted to the appellate court for disposal in accordance with law after giving liberty to the appellant to adduce further evidence. The plaintiff shall be entitled to lead evidence in rebuttal. In the circumstances of the case, the parties shall bear their own costs in this Court. I would like to caution the learned court not to be mislead by any observation made by me. I have expressed no opinion about the merit of the case but I have only decided the legal question which I was called upon to decide. The appellate court is directed to decide the appeal within two months from the date of receipt of a copy of the judgment. The office shall send the records at once.