Musnad Ahmad

It was narrated that ‘Ali (رضي الله عنه) said: You recite: `after the payment of legacies he may have bequeathed or debts` [an-Nisa` 4:12]. The Messenger of Allah (ﷺ) ruled that debts must be paid before carrying out bequests, [And he ruled] that sons from the same father and mother inherit from one another, but sons from different mothers (but the same father) do not. A man inherits from his brother through his father and mother but not from his brother through his father only.