Ghiro ( lease) land reg

My Father has given money to Land Owner for Agri Land for Lease still he returend money to us. You may called GHIRO of Land. land Owner asked more money in sub sequent year and money has been given in Stamp Paper which was signed by Land Owner and my father. No Registry has been made to any where. Local Lawyer informed that this stamp paper has no value. Kindly advise how to make it legal documents.