Is the seller's demand to own part of the land he sold to my father in 1963, and his claim that the remainder is a trust for others, after he divided the alleged trust in 1982, considered valid, especially after my father's death?

Cases and disputes such as those mentioned must be presented before the Sharia judiciary, as issuing a fatwa regarding them is difficult.

Not every claim is accepted and heard. A claim that is contradicted by custom and habit is not heard. An example of this is when a person buys land and disposes of it for more than thirty years, and the seller remains silent, then the seller later claims that a portion of it was a trust with him.

If the Sharia judge deems the claim worthy of being heard and it is proven that a portion of the land does not belong to the deceased, and evidence is established for this, then the heirs must return it to its owners and claim its price from the seller.