Sale of agricultural land in Bihar to outsider.

I wanted to sell an agricultural piece of land located in Bihar. That land belongs to my ancestors. I made a verbal agreement with a person who has paid me an advance payment towards the land deal. However, there is another person who has turned up to purchase the land now, and he claims that he is an owner of an adjacent plot to my land which I want to sell and he claims that I can only sell it to a person like him who is adjacent plot owner.

He has threatened to file a law suit if we go ahead with our land sale with the first person who has paid us the advance. I want to know if there is any such law where I MUST sell my land to only adjacent land holders. If yes, then if I go back and cancel my verbal agreement with the first person and return his cash, can a case of cheating be filed against me? What should I do? Ideally I wish to keep my original agreement intact.