Is it obligatory to disburse the cost of educating and marrying the youngest son from the deceased father's estate before or after its division, by analogy with Allah's saying: "after any bequest he may have made or debt," and His (peace be upon him) saying: "I do not bear witness to injustice. Fear Allah and be just among your children"?

The son's maintenance is obligatory upon the father during his lifetime, subject to its conditions. If the father dies, the wealth becomes inherited property, and the son has no right to demand his father's maintenance after his death. Rather, he is like the other heirs, and he has what Allah has ordained for him from the inheritance. If the father gifted money to his son during his lifetime, and the son did not receive it until his father died, the son has no right to claim it. Likewise, the father's bequest to his heir son is not enforceable unless the heirs permit it, due to the Prophet (peace be upon him) saying: "Indeed, Allah has given every rightful person his right, so there is no bequest for an heir." Therefore, it is not obligatory for you to pay for your younger brother's education and marriage from the estate, but it is permissible to donate that to him willingly.