How is an inheritance divided among three sons, two daughters, and a wife, given a will to make one of the houses an endowment (waqf) and spend its annual rent on charitable projects?

If a man dies and leaves behind a wife, three sons, and two daughters, and no other heirs, then his wife receives one-eighth due to the existence of a direct descendant, in accordance with the Almighty's saying: "But if you have a child, then for them is one eighth of what you leave." The remainder goes to the sons and daughters by way of ta’sib (residuary inheritance), with the male receiving the share of two females, in accordance with the Almighty's saying: "Allah instructs you concerning your children: for the male, what is equal to the share of two females."

As for a bequest of waqf (endowment) contingent upon death, it is valid and is considered from one-third of the estate, as reported by Imam Ahmad and mentioned by Ibn Qudamah, who cited the bequest of Umar ibn al-Khattab (may Allah be pleased with him) as evidence. Accordingly, the father’s bequest to endow the house is valid if it does not exceed one-third of his estate. If it exceeds that, it is not executed except up to the amount of one-third, unless the adult and mature heirs consent to it.