Is the gift contract between the father and his son valid, given the absence of one of the two just witnesses at the time of its documentation, and is it permissible for him to sign it later, and in the event of its invalidity, what is the ruling on the son's dispositions concerning the land?

In religious terms, a gift (hiba) does not require witnessing or documentation; it is sufficient for the donee to take possession with the permission of the donor, as Abu Bakr did with his daughter Aisha. However, in judicial proceedings, its proof necessitates evidence such as the testimony of two upright witnesses, or one man and two women, or one man and the oath of the claimant, or the admission of the donor. If the gift is completed and proven, the son may dispose of the gifted land, with the obligation of ensuring justice among all children.