(16, 17) باب الْقِصَاصِ فِي السِّنِّ
It was narrated from Samurah that the Prophet of Allah said:
"Whoever castrates his slave, we will castrate him, and whoever mutilates his slave, we will mutilate him." This is the wording of Ibn Bashshar (one of the narrators).
Reference: Sunan an-Nasa'i 4754
In-book reference: Book 45, Hadith 49
English translation: Vol. 5, Book 45, Hadith 4758