Has he specifically asked for NOC from your wife in the ensuing agreement?, if so whether it was in writing, if it was in writing, ask him to show the clause in the agreement that you should obtain NOC, if he is torturing you orally, you issue him a notice stating that despite giving him sufficient chances to register the property in his name by paying the balance o sal consideration amount,he is unnecessarily troubling you by evading to register the property at his expenses for the reasons best known to him and from his attitude it can be evidently seen that either he is not interested or he is having sufficient funds to get the sale deed registered and executed in his favor by paying the balance of sale consideration amount, thus,it is proved that he is unable to perform his part of the contract, hence he is given a notice as a last chance to come forward to register the property on his name by paying balance of sale consideration amount within (the time to be stipulated by you), thereby, upon the failure on his part to perform his part of contract, the money paid by him towards advance for purchase of the property stands forfeited.
This is how you have to issue him with a legal notice either by yourself or through your advocate and this notice will take care of all other requirements, because he either has to comply with the demands made in the notice or he has to give a reply to the notice stating his reasons after which you can initiate necessary legal action based on the contents of his reply.
