What is the ruling of Islamic law regarding a sixty-year-old man who has no children writing a sales contract to his wife to secure her right to the house from distant relatives who intend to seize the house after his death? And do these relatives have a right to inheritance?

If the man’s intention in writing his house to his wife is to transfer its ownership to her after his death, then it is a bequest to an heir, which is impermissible unless approved by the mature and sane heirs. If the intention is to transfer ownership to her during his lifetime, then it is a gift that is permissible, provided there is proper possession. However, it is not permissible if the intention is to deprive other heirs.

Regarding the heirs: If the man dies leaving only his wife and the relatives you mentioned, the wife inherits one-quarter, and the remaining three-quarters of the estate go to his closest male agnates. The other relatives have no right, as the Prophet, peace and blessings be upon him, said: "Give the prescribed shares to those who are entitled to them; then whatever remains is for the closest male agnate." It is preferable to refer inheritance cases to the court for a ruling.