Ja'far bin Muhammad (may Allah have mercy on him) said: I heard al-Hakam bin Utaybah asking my father, who had placed his hand on the wall of the grave in order to stand up: Did the Prophet (peace and blessings be upon him) judge by an oath and a witness? He said: Yes, and Ali (may Allah be pleased with him) also judged by it among you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20675