كتاب المظالم
Read the English translation first, with the original Arabic directly underneath.
Narrated Um Salama:
(the wife of the Prophet) Allah's Messenger (ﷺ) heard some people quarreling at the door of his dwelling. He came out and said, "I am only a human being, and opponents come to me (to settle their problems); maybe someone amongst you can present his case more eloquently than the other, whereby I may consider him true and give a verdict in his favor. So, If I give the right of a Muslim to another by mistake, then it is really a portion of (Hell) Fire, he has the option to take or give up (before the Day of Resurrection).
إِنَّمَا أَنَا بَشَرٌ وَإِنَّهُ يَأْتِينِي الْخَصْمُ، فَلَعَلَّ بَعْضَكُمْ أَنْ يَكُونَ أَبْلَغَ مِنْ بَعْضٍ، فَأَحْسِبُ أَنَّهُ صَدَقَ، فَأَقْضِيَ لَهُ بِذَلِكَ، فَمَنْ قَضَيْتُ لَهُ بِحَقِّ مُسْلِمٍ فَإِنَّمَا هِيَ قِطْعَةٌ مِنَ النَّارِ، فَلْيَأْخُذْهَا أَوْ فَلْيَتْرُكْهَا