JUDGMENT : P. S. Mishra, J. - This appeal by the defendant is directed against a JUDGMENT : of affirmance. The courts below have granted to the plaintiff-respondent a decree for specific performance of contract, in respect of the lands mentioned in schedule I of the plaint. The defendant has, accordingly, been asked to receive a sum of Rs. 3,000/- and to execute sale deed in favour of the plaintiff respondent in respect of the said land. The defendant has appealed, to this court against the said decree. 2. In the maze of facts, that are stated in the plaint, the written statement, and the JUDGMENT : of the courts, below, only a few need mention. It is the admitted case of the parties that the defendant-appellant and the plaintiff-respondent agreed to sell 17 dhoors of land and accordingly a Mahadnama (Ext. 4) was duly executed on 29.9.1972 and registered. The Mahadnama mentioned a consideration of Rs.6000/- for the outright sale of the properly described therein by the defendant in favour of the plaintiff. On its execution a sum of Rs. 3,000/- was paid by the plaintiff to the defendant as part payment and the remaining 3,000/- was to be paid on the execution of the sale deed. 3. The plaintiff, however, according to his case, noticed that Mahadnama (Ext. 4) contained a wrong description of the property, agreed to be sold by the defendant to him instead of the property for which the same was executed. According to the plaintiff, the agreement between the plaintiff and the defendant was to sell 17 dhoors of land as described in schedule I of the plaint. The description in the Mahadnama (incorporated in schedule 2 of the plaint) of the property to be vended by the defendant, was varied in connivance with the scribe by the defendant. The plaintiff served a notice upon the defendant accordingly and asked him to execute the sale deed as per the agreement, the defendant answered the said notice stating that the agreement was to sell the property as described in the Mahadnama. Hence the plaintiff instituted the suit claiming, on the• basis of the agreement, to sell the properties described in schedule I of the plaint, and sought a decree for specific performance of contract. 4. Hence the plaintiff instituted the suit claiming, on the• basis of the agreement, to sell the properties described in schedule I of the plaint, and sought a decree for specific performance of contract. 4. The defendant's case is that the agreement for sale is in respect of the property as described in the Mahadnama and that property he is inclined to sell but not a property for which there has been any agreement. There were other objections as to the maintainability of a suit for specific performance, including non-compliance of the provisions of section 16 (c) of the Specific Relief Act raised on his behalf. 5. The courts below have determined the question (1) whether the appellant and the respondent had agreed to sell 17 dhoors of land mentioned in schedule 1 of 17 dhoors of land mentioned in schedule 2 of the plaint : (2) whether the defendant-appellant got the wrong description of the land to be vended incorporated in the Mahadnama in connivance with the scribe; and (3) whether the plaintiff-respondent is entitled to a decree to the specific performance of contract, in favour of the plaintiff-respondent. At the time of admitting this appeal to hearing the question of law indicated was, whether the plaintiff has been able to plead and prove in accordance with law the requirements of section 16(c) of the Specific Relief Act. Mr. Shashi Shekhar Dwivedi, learned counsel appearing for the appellant has, however, prayed to raise one more contention of' law, namely, whether a party to the agreement could plead and prove any fact standing at variance with the contents of the document duly executed and registered in accordance with law or not. 6. Having appreciated the effect of the question that Mr. Dwivedi has proposed to raise, I have permitted him to do so. Accordingly, this appeal has been heard on two questions, namely, (1) whether the plaintiff has been able to plead and prove in accordance with law the requirements of section 16(c) of the Specific Relief Act; and (2) whether the plaintiff could/can plead and prove a fact to vary/modify the contents of the deed of agreement and consequentially claim specific performance of contract with such variations. 7. 7. I propose to deal in my JUDGMENT : the two contentions in the reverse ORDER :for the answer to the second question of law given in favour of the defendant appellant shall make the suit incompetent and it shall be no longer necessary to decide whether section 16 (c) of the Specific Relief Act has been complied with in the instant case or not. 8. Section 91 of the Evidence Act excludes oral evidence when the terms of a contract or of a grant or of any other disposition of property is reduced to the form of a document. The rule with regard to writings is that oral proof cannot be substituted for the written evidence of any contract which the parties have put into writing (See, A. I. R. 1923 Privy council 50) it is a cardinal rule of evidence, not one of technicality, but of substance, that where written documents exist, they shall be produced as being the best evidence of their own contents. It has to be seen, however, whether identity of the contracting parties or subject matter can be regarded as a term of the contract, so as to exclude oral evidence (See A. I. R. 1958 S. C. 448). Where a contract is entered into between parties. the Contract deals with the subject matter as well as the persons between whom it is entered into, and the names of the parties or the subject matter in so far as they relate to terms which create obligations cannot be regarded as so divorced from the terms of the contract, that evidence may be led to show that some other persons intended to incur obligations under the contract instead of the parties designated, therein or the contract concerns some other subject matter ( See A. I. R. 1956 Bombay 165). True a contract for sale may be oral and it is not required- by law to be reduced to ('he form of a documents and in all cases in which any matter is required by law to be reduced to the form of a document no evidence shall be given in proof of the terms of such contract, or of such matter, except the document itself. Section 91 of the Act uses the conjunctive 'and' to co-ordinate the words "have been reduced to the form of a document 'and' in all cases in which any matter is required by law to be reduced to the form of a document". Section 92 of the Evidence Act, which incorporates the excepting, however, uses the disjunctive 'or' to disjoin the words ‘the terms of any such contract’ or 'any matter required by law to be reduced to the form of a document' This section supplements section 91. The two sections, however, differ in some material particulars. If section 92 does not apply there is no reason to exclude evidence about an oral agreement solely on the ground that if believed the said evidence may vary the terms of the transaction. The other alied provisions namely, sections 93 to 99 are not very relevant for the case in hand, yet a reference to section 93 may be of some use, which says 'when the language used in a document is, in its face, ambiguous or defective, evidence may not be given of facts which would show its meaning or supply its defects. It follows, therefore, where words of any written instrument are free from ambiguity in themselves and where external circumstances do not create any doubt or difficulty as to the proper application of those words to claimant under the instrument, or the subject matter to which the instrument relates, such instrument is always to be construed according to the strict plain common meaning of the words themselves and in such cases evidence de hors the instrument for the purpose of explaining it according to the surmised or alleged intention of the parties to the instrument is utterly inadmissible (See A.I.R. 1932 Privy Council 255). While construing a written contract the court will be erring in approaching the question of what formed the subject matter of the negotiations which preceded the written contract between the parties, without first settling to what extent the contract was so ambiguous as to justify resort to evidence as to the negotiation (See AIR 1946 PC 50) where a condition in written contract is held to be vague or uncertain no evidence can be admitted by virtue of section 93 to remove the said vagueness or uncertainty. 9. 9. I have set forth the basis to indicate that the document (Exhibit 4) which spelled out the contract in respect of the property described therein, is the document that binds the parties. It is not the case of the plaintiff respondent that the agreement of sale is de hors, the document (Exhibit 4). Undoubtedly, the plaintiff could plead and prove oral agreement for sale. There is no such case. The case pleaded is one, in which a deliberate variation by the defendant in the document in connivance with the scribe has been alleged. It is obviously a case in which the plaintiff has tried to vary the terms of the contents in Exhibit 4 by parol evidence. Assuming for argument sake that the plaintiff is not excluded from leading parol evidence to explain the terms of the contract as to the identity of the land, yet, a strong presumption has to be attached to the document. Inference has to be drawn against the plaintiff, unless there is strong evidence to show that he signed the document in ignorance. 10. The evidence that has been taken into consideration by the court of appeal below, is primarily a mention in exhibit 4 that the defendant had agreed to sell the western portion of plot no. 3818 to the plaintiff. There arc oral testimonies of two witnesses, namely, P.W. 4, who has said that the agreement was arrived at in his presence and the land to be vended was stated to be located near the D. A. V. school at Siwan; the defendant, according to him, also disclosed the boundary of the land, for which Mahadnama was to be executed and the boundary disclosed was one as described in schedule I of the plaint; and P.W. 5 the respondent plaintiff himself, who bas said that the entire area of the land of plot no. 3818 is 11 kathas and it was purchased by Mahgoo Ram; sons of Mahgoo Ram had partitioned the land of plot no. 3818; western portion of the said plot fell to the share of Hari Prasad; and the defendant appellant agreed to sell 17 dhoors of the land to him forming the western portion of plot no. 3818 for a sum of Rs. 6,000/-. How on this evidence the court can hold that son of Maghoo Ram bad partitioned the property and western portion of plot no. 3818 for a sum of Rs. 6,000/-. How on this evidence the court can hold that son of Maghoo Ram bad partitioned the property and western portion of plot no. 3818 had fallen to the share of defendant-appellant and that he had agreed to sell the said portion to the plaintiff-respondent, but got the same varied and introduced a wrong description of the land in the document (Ext. 4). The evidence is undoubtedly insufficient for any such finding. The error of law is writ large in the fact that on such evidence only the courts below have held that the plaintiff- respondent has been able to prove that there was a contract to sell the land described in Schedule I of the plaint and not as described in the Mohadnama. 11. The above error of law apart, there is yet another serious error of law. Suit for specific performance of contract of sale requires a special pleading. Section 16(c) of the Specific Relief Act says that the specific performance of a contract cannot be enforced in favour of a person, who fails to aver and prove that he has performed or has always been ready and willing to perform the essential terms of the contract which are to be performed by him, other than terms the performance, of which has been prevented or waived by the defendant. Explanation (ii) for the purpose of clause (c) above says- "the plaintiff must aver performance of or readiness and willingness to perform, the contract according to its truse construction. Assuming that the true construction arrived at by the courts below is that there has been a contract of sale of the properties described in schedule I of the plaintiff the plaintiff-respondent was required to state that he has always been ready and willing to perform the essential terms of the contract and prove that he has performed or has always been ready and willing to perform the essential terms of contract. Repudiation of the contract by the defendant does not relieve the plaintiff of this obligation. 'Ready' means prepared or having all ‘preparations made to do something’ and willing, means having a ready will. Repudiation of the contract by the defendant does not relieve the plaintiff of this obligation. 'Ready' means prepared or having all ‘preparations made to do something’ and willing, means having a ready will. This court has reiterated more than once that in a suit for specific performance of contract the requirement of section 16(c) of the Specific Relief Act as to avernment and proof of plaintiffs readiness and willingness to perform his part of the contract is a mandatory one (See 1977 P. L. J. R. 465; 1979 B. L. J. R. 667) There is complete absence of appropriate pleading and proof in this regard. The court of appeal below has considered at some length, whether time was the essence of the contract or not, but has failed to take notice of this serious lacuna in the plaintiffs case. It was for the plaintiff to establish that he was since the date of the contract continuously ready and willing to perform his part of the contract and to -prove in the event of the same being controverted. This court has also pointed out that not only it should be avered in the plaint but also should' be stated in court during trial, otherwise readiness until the end of the trial cannot be indicated at the time of the filing of the suit. The court of law in such a situation has to refrain from granting any decree for specific performance of contract. 12. For the said two errors of law, I am of the considered opinion that the JUDGMENT :s of the courts below are vitiated on account of serious errors of law. 14. In result this appeal is allowed. The JUDGMENT : and decree of the court of appeal below are set aside and the suit of the plaintiff-respondent is dismissed. But in the circumstances of the case, there shall be no ORDER :as to costs.