كتاب الأقضية
30  
The Book of Judicial Decisions
(3)
Chapter: So the judgement of the judge does not change what happened
(3)
باب الْحُكْمِ بِالظَّاهِرِ وَاللَّحْنِ بِالْحُجَّةِ ‏‏
Sahih Muslim 1713 a

Umm Salama reported Allah's Messenger (ﷺ) as saying:

You bring to me, for (judgment) your disputes, some of you perhaps being more eloquent in their plea than others, so I give judgment on their behalf according to what I hear from them. (Bear in mind, in my judgment) if I slice off anything for him from the right of his brother, he should not accept that, for I sliced off for him a portion from the Hell.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ، أَخْبَرَنَا أَبُو مُعَاوِيَةَ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ زَيْنَبَ بِنْتِ أَبِي سَلَمَةَ، عَنْ أُمِّ سَلَمَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ إِنَّكُمْ تَخْتَصِمُونَ إِلَىَّ وَلَعَلَّ بَعْضَكُمْ أَنْ يَكُونَ أَلْحَنَ بِحُجَّتِهِ مِنْ بَعْضٍ فَأَقْضِي لَهُ عَلَى نَحْوٍ مِمَّا أَسْمَعُ مِنْهُ فَمَنْ قَطَعْتُ لَهُ مِنْ حَقِّ أَخِيهِ شَيْئًا فَلاَ يَأْخُذْهُ فَإِنَّمَا أَقْطَعُ لَهُ بِهِ قِطْعَةً مِنَ النَّارِ ‏"‏ ‏.‏
Reference : Sahih Muslim 1713a
In-book reference : Book 30, Hadith 4
USC-MSA web (English) reference : Book 18, Hadith 4247
  (deprecated numbering scheme)