Musnad Abu Ya'la al-Mawsili 209:19

Muhammad ibn Abdullah al-Azdi narrated to us, Safwan ibn Isa narrated to us, Usamah ibn Zayd al-Laythi narrated to us, from Abdullah ibn Rafi’, the freed slave of Umm Salamah, from Umm Salamah, who said: Two men came to the Prophet, peace and blessings of Allah be upon him, disputing over inheritances and things that had become obscure. The Messenger of Allah, peace and blessings of Allah be upon him, said: "I only judge between you according to my opinion as long as nothing has been revealed to me. So, whoever I judge in favor of, based on an argument I see, and he thereby seizes a portion [of property] unjustly, he is only seizing a piece of Hellfire, a brand, which he will bring upon his neck on the Day of Resurrection." She said: The two men wept, and each of them said: "O Messenger of Allah, my right is for my companion." The Messenger of Allah, peace and blessings of Allah be upon him, said: "No, but go, seek what is most accurate, then draw lots, and then let each of you absolve the other."