Sayyidah Umm Salamah (may Allah be pleased with her) said: I was sitting with the Prophet (peace and blessings be upon him) when two men of the Ansar came, disputing with each other over some things that had become old and effaced. The Prophet (peace and blessings be upon him) said: "I judge between you only in matters about which nothing has been revealed to me. So whoever I rule in favour of on the basis of an argument I see, and he thereby takes some of his brother's property unjustly, will come on the Day of Resurrection with a flaming iron rod around his neck." Both men began to weep, and each said: O Messenger of Allah, the right that I am claiming is his. He (peace and blessings be upon him) said: "No; rather go, cast lots and aim for what is right, then let each of you absolve the other."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلح / 11359