What is the ruling of Islamic law regarding a husband's cession of a piece of barren land to his wife through an informal document lacking witnesses, a date, and specific identification of the property, given the existence of another heir (a half-brother)? Is this cession valid?

Ownership of the land does not become established for the wife unless she takes possession of it during the husband's lifetime and this is proven by evidence or by the acknowledgment of the heirs. If this does not occur, the land becomes part of the deceased husband's estate, and the wife takes one-fourth due to the absence of a direct descendant heir. The brother inherits the remainder by ta'sib (agnatic succession) if he is a full or paternal brother. It is recommended to refer to the competent courts regarding these matters.