Once the execution of agreement to sell and the payment of advance substantial sale consideration is admitted by the vendor, nothing further is required to be proved by the vendee.

Specific Relief Act, 1963 - Suit for specific performance for agreement to sell - Once the execution of agreement to sell and the payment of advance substantial sale consideration is admitted by the vendor, nothing further is required to be proved by the vendee. (Para 5.2) 

P. Ramasubbamma v. V. Vijayalakshmi, 2022 LiveLaw (SC) 375 : AIR 2022 SC 1793 : (2022) 7 SCC 384