Sayyiduna Ali (may Allah be pleased with him) said: "You recite, 'after any bequest that is made or a debt' [Surah al-Nisa': 12], yet Allah Almighty has decreed (payment of) the debt before the bequest; and the full siblings (children of the same mother) take precedence over the paternal half-siblings in inheritance."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12562