Sale of legally disputed land

A man sold my father an agriculture land which was in legal dispute and my father gave him mony after agreeing on terms that if he wins the case in future and get the ownership of land he will sale that land to my father. Now, he won the case of specific performance but he is denying to sale that land to my father, what are legal remedies my father can take on that man on behalf of that agreement. Details of the case are- 1.The man is not the owner he was agreement holder from the original owner. The man won the case in future for specific performance of agreement in the year 2019. Case was filed in the year 2005. 2.The date of the Agreement between my father and the man was 02/05/2006 in which he promised if he wins the case he will sale that land to my father the amount for the land was already given by my father. There is no specific date mentioned in the agreement to execute it says wherever the court orders comes in his favour he will sale it to my father.