سنن ابن ماجه

It was narrated that 'Ali said: “The Messenger of Allah (ﷺ) ruled that the debts should be paid off before the execution of the will. You recite: '(The distribution in all cases is) after the payment of legacies he may have bequeathed or debts.' The sons of one mother (from the same father) inherit from one another, but not the sons from different mothers (but the same father).”