It was narrated from Salamah bin Rawh bin Zinba', that :
his grandfather came to the Prophet (ﷺ) and he had castrated a slave of his. The Prophet (ﷺ) manumitted the slave in compensation for having been mutilated. (ES)
English reference (ES): Vol. 3, Book 21, Hadith 2679 (ES)
Arabic reference (ES): Book 21, Hadith 2781 (ES)