Musnad Ahmad 882
It was narrated that ‘Ali (رضي الله عنه) said:
The Messenger of Allah (ﷺ) sent me to Yemen. I said: O Messenger of Allah, you are sending me to people who are older than me, and I am young and do not know how to judge. He put his hand on my chest and said: `O Allah, make his tongue steadfast and guide his heart. O Ali, when two disputants sit before you, do not judge between them until you listen to the second one as you listened to the first. If you do that, the verdict will become clear to you.” ‘Ali said: I never got confused about any judgement after that or doubted a verdict after that.
حَدَّثَنَا أَسْوَدُ بْنُ عَامِرٍ، حَدَّثَنَا شَرِيكٌ، عَنْ سِمَاكٍ، عَنْ حَنَشٍ، عَنْ عَلِيٍّ، رَضِيَ اللَّهُ عَنْهُ قَالَ بَعَثَنِي رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِلَى الْيَمَنِ قَالَ فَقُلْتُ يَا رَسُولَ اللَّهِ تَبْعَثُنِي إِلَى قَوْمٍ أَسَنَّ مِنِّي وَأَنَا حَدِيثٌ لَا أُبْصِرُ الْقَضَاءَ قَالَ فَوَضَعَ يَدَهُ عَلَى صَدْرِي وَقَالَ اللَّهُمَّ ثَبِّتْ لِسَانَهُ وَاهْدِ قَلْبَهُ يَا عَلِيُّ إِذَا جَلَسَ إِلَيْكَ الْخَصْمَانِ فَلَا تَقْضِ بَيْنَهُمَا حَتَّى تَسْمَعَ مِنْ الْآخَرِ كَمَا سَمِعْتَ مِنْ الْأَوَّلِ فَإِنَّكَ إِذَا فَعَلْتَ ذَلِكَ تَبَيَّنَ لَكَ الْقَضَاءُ قَالَ فَمَا اخْتَلَفَ عَلَيَّ قَضَاءٌ بَعْدُ أَوْ مَا أَشْكَلَ عَلَيَّ قَضَاءٌ بَعْدُ‏.‏