The Messenger of Allah ﷺ said to me, "When two men bring a dispute before you, do not rule in favor of the first until you have heard what the other has to say. Then you will know how to judge."Ali said, "I never wavered as a judge after that."
حدثنا هناد حدثنا حسين الجعفي عن زائدة عن سماك بن حرب عن حنش
قال لي رسول الله ﷺ إذا تقاضى إليك رجلان فلا تقض للأول حتى تسمع كلام الآخر فسوف تدري كيف تقضي قال علي فما زلت قاضيا بعد
[Its chain is daif]. Ahmad (1/90) narrated it from Husayn Jufi, and Abu Dawud (3582) narrated it from the hadith of Simak, with the same wording. Hakim (4/93) graded it sahih, and Dhahabi agreed.Hanash bin Mutamir was declared daif by the majority, but his hadith has supporting evidence in meaning.