Sunan Ibn Majah, Volume 3, Book 21, Hadith 2679 (DarusSalam) ⓘ
It was narrated from Salamah bin Rawh bin Zinba', that : his grandfather came to the Prophet and he had castrated a slave of his. The Prophet manumitted the slave in compensation for having been mutilated.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا عَبْدُ السَّلاَمِ، عَنْ إِسْحَاقَ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي فَرْوَةَ، عَنْ سَلَمَةَ بْنِ رَوْحِ بْنِ زِنْبَاعٍ، عَنْ جَدِّهِ، أَنَّهُ قَدِمَ عَلَى النَّبِيِّ صلى الله عليه وسلم وَقَدْ خَصَى غُلاَمًا لَهُ فَأَعْتَقَهُ النَّبِيُّ صلى الله عليه وسلم بِالْمُثْلَةِ .
also referenced under: Hadith 2679 (Reference) & Book 21, Hadith 2781 (In-Book)