of charity and the reward of maintaining kinship; from this it follows that a person may give voluntary charity to his children when they are in need, and to his wife, and likewise a wife may give to her husband, and that such giving counts both as sadaqah and as the nurturing of family bonds.
As for the obligatory zakat: if the expense he intends to cover is something he is already required to provide, it is invalid for him to discharge his zakat to them. For instance, if the zakat would be used for their living expenses while he is legally responsible for those expenses and his means allow it, he may not give them zakat. If, however, the matter is not one of his legal obligations—such as paying a debt owed by his father, his son, or his wife, or a wife paying a debt owed by her husband—there is no harm in that so long as the debtor is alive. Should the debtor have died, the debt may be settled only as a voluntary act of charity or from the estate, not from zakat.
16/327—It is narrated from Abu Sufyan Sakhr ibn Harb (may Allah be pleased with him), in his lengthy account of Heraclius, that Heraclius asked him, “What does he—meaning the Prophet ﷺ—command you?” Abu Sufyan replied, “He says, ‘Worship Allah alone without associating anything with Him, abandon what your forefathers say, and he commands us to perform prayer, speak the truth, practice chastity, and maintain ties of kinship.’” Agreed upon.
18/328—Abu Dharr (may Allah be pleased with him) reported that the Messenger of Allah ﷺ said, “You will conquer a land in which the qirāṭ is mentioned.”