Judgment : This appeal is against the judgment of partial reversal. The plaintiff instituted the suit for declaration of his title to the property being plot No. 636 on the basis of his purchase from the admitted owners, Reajuddin and Rihima Khatun on the 16th of January, 1958. The case made was that the deed of sale was executed by the constituted attorney of the said owners, defendant No.2, Kalipada, who is the father of the plaintiff, on the basis of a general power dated the 17th of August, 1955, exhibit 4. The prayer was for declaration of title on the basis of the said purchase and confirmation of possession. 2. The suit was contested by defendants Nos. 4 to 7 who purchased the suit plot from defendant No, 1. Their case was that the aforesaid owners exchanged their plot No. 636 for plot No. 490 and this was rectted in their general power of attorney dated the 22nd of February, 1955 which is exhibit D. In view of this clear recital which was an admission of exchange of the property in favour of defendants Nos. 1, 2 and 3 it was submitted that the plaintiff did not acquire any title to the property by purchase as the aforesaid owners had no longer any title to transfer to the plaintiff. The suit was contested by defendants Nos. 1 to 7 but at the trial only defendants Nos. 1 and 4 to 7 contested. The learned Munsif decreed the suit on trial on evidence. 3. On appeal the appellate Court was of the opinion that the plaintiff did not acquire any title to the property and he was estopped from asserting his title in view of the admissions made by his vendors about the earlier exchange of the suit property in favour of the defendants against another property, as already indicated. Further the plaintiff had no possession to the suit property as would appear from the relevant entries in the record of rights, In this view of the matter the learned appellate Court varied the decree of the trial Court, declared plaintiff's interest in 2/3rd share in the disputed properties as defendants Nos. 2 and 3 who view of the contest made by defendant No.1 and his purchasers, defendants Nos. 2 and 3 who view of the contest made by defendant No.1 and his purchasers, defendants Nos. 4 to 7, the Court declared the plaintiff's title in respect of the 2/3rd share in the property excluding 1/3rd share which it was held, had were owning the aforesaid share did not contest the suit at the hearing. In vested in defendants Nos. 4 to 7 in the mean time. The appeal was allowed in part on contest. The plaintiff preferred this appeal against that aforesaid decree. 4. Mr. Mukherjee drew my attention to section 26C of the Bengal Tenancy Act which provides that every transfer of raiyati interest in any holding can only be done by a registered instrument. In the instant case defendants Nos. 1 to 3 did not acquire any interest in absence of a registered instrument. Accordingly they never acquired any title to the suit property and the purchasers from, defendant No. 1, being defendants Nos. 4 to 7 did not acquire any title therein. 5. It is obvious that in view of the provisions of section 26C any transfer of the occupancy holding can only be made by a registered instrument. In absence of such transfer, it is not possible to hold that any title passed in favour of the transferee. Mere recital in a power of Attorney about the exchange of the suit plot will not confer any title on the purported transferees in the absence of any registered instrument. There is, therefore, no escape from that conclusion that in absence of any registered deed of exchange, a mere recital by the vendors of the plaintiff who where the erstwhile owner of the property, would not confer any title to the defendants in whose favour the purported exchange is said to have, been made. 6. Mr. Sen Gupta referred to the decision in (1) Madho v. Mukund, reported in AIR 1955 SC 481 in support of the proposition that the vendors of the plaintiff were estopped from asserting any title contrary to the admissions made in the earlier document, namely, the Power of Attorney. In this decision, the Supreme Court has laid down that estoppel is a rule of evidence which prevents a party from alleging and proving the truth. If it does not strictly apply, the rule of election in appropriate cases may be applicable. In this decision, the Supreme Court has laid down that estoppel is a rule of evidence which prevents a party from alleging and proving the truth. If it does not strictly apply, the rule of election in appropriate cases may be applicable. This rule precludes a person, who with full knowledge of his rights, has once elected to assent to a transaction voidable at his instance, and, has selected not to exercise his right to avoid it, from going back on that and avoiding it at a later stage. Having made an election, he is bound by, it. It is not clear how this proposition helps Mr. Sen Gupta. It may be that in appropriate cases there may, be a question of estoppel. But it is also the settled position that estoppel is not available against the provisions of a statute. The mere recital of the factum of an exchange cannot in effect operate as an exchange when the requisities required for a valid exchange like registration of the document is absent as in the instant, case. 7. Mr. Sen Gupta next submitted that the subsequent Attorney, the defendant No.2, was the attesting witness of the earlier Power of Attorney. In (2) Bhagaban Singh v. Ujagar, reported in AIR 1928 PC 20 it has been held that mere attestation of a document may not create an estoppel but where one has knowledge of the contents of the document and consents to the transaction, it will amount to estoppel. The demurrer to this contention is the same as stated earlier that there cannot be any estoppel against the provisions of the Statute. 8. Mr. Sen Gupta has further stated that in the earlier Power of Attorney, Exhit 'D', there are more specific and detailed recitals about the suit land while the subsequent Power of Attorney was a mere general statement of authorisation, so that, it should not prevail against the earlier document. This contention also fails against the doctrine that there cannot be any estoppel against the Statute. The defendants 1 to 2 and 3 not having acquired the property by exchange on the basis of a registered document validly made are not entitled to claim any title on the basis thereof. This contention also fails against the doctrine that there cannot be any estoppel against the Statute. The defendants 1 to 2 and 3 not having acquired the property by exchange on the basis of a registered document validly made are not entitled to claim any title on the basis thereof. Accordingly, the defendants 4 to 7 who claim title through defendant No. 1 cannot have any preferential claim against the plaintiff, who had otherwise acquired the property by registered conveyance from the admitted owners though executed by a Constituted Attorney on the basis of Power of Attorney which factum has not been disputed. 9. The appellate Court found the plaintiff's possession in respect of 2/3rd share and the plaintiffs title and possession in respect whereof to the said extent was not disputed by the defendants. Further the period is too short to extinguish the plain tiff's possession the defendant's possession commencing from not earlier than 1955 while the suit was instituted in 1960. 10. In the premises, the learned Judge of the appellate Court was in error in disallowing the claim of the plaintiff against the defendant No.1 while admitting the same against the other two defendants merely on the view that they did not contest the claim. If there was a valid exchange as found by the appellate court, the plaintiff would have never acquired any interest in the property. In view of the position as indicated above, the appeal succeeds and is allowed without however any order as to costs. The judgment and decree under appeal in respect of the 1/3rd share of the defendant No.1 are set aside and those of the learned Munsif restored and affirmed. Parties will be at liberty to take back the documents filed by them in this court after the judgment is signed.