Send a legal notice to the buyer, after [deleted], stating that you have cancelled the Agreement of Sale, due to the following reasons:-
(1) Since the Agreement of Sale is barred by limitation, as the date of executing the deed was on [deleted] and so far the Absolute Sale Deed had not been executed ( [deleted] ).
(2). Moreover, the prospective buyer has not paid you a single rupee. The buyer has to prove on record that he had indeed paid you an advance amount of Rs. 5 Lakhs, which the buyer cannot prove, as there will be no record of either Cheque/DD/Bank Transfer, etc. If the buyer says that he has paid you the advance amount by cash, then there have to be the signature of 2 independent witnesses.
(3). As per rules, any transaction above Rs. 20000/- can only happen through Cheque/DD/Bank Transfer. So the Buyer cannot say that he paid you Rs. 5 Lakh by cash.
(4). Notary's entry does not give him the advantage, since the registration of the Agreement of Sale has not been made.
(5). To be legally valid, the agreement of sale had to be made on 0.1% of the value of the property. Hence the buyer will be at disadvantage that the agreement was made only on Rs. 100/- Stamp Paper.
(6). It's your free Will to back off, based on the above points.
(7). If you don't get response after serving legal notice to him, publish your intention of cancelling the agreement of sale in local newspapers in vernacular and English languages.
(8). When you back out, at best, the buyer will approach the Court and he can't prove that he paid you the advance amount of Rs. 5 Lakhs, as there's no bank record, as well as the 3 years' limitation period will also be expiring on [deleted].
(9). An Agreement of Sale will not have any legal validity, if there's no advance amount towards consideration paid to the Seller by the prospective Buyer.