Musannaf Ibn Abi Shayba 33:626

Waki’ narrated to us, he said: Al-A’mash narrated to us, from Mundhir, from Rabi’ ibn Khuthaym, that he used to sweep the privy himself. He said: It was said to him, "You are spared from this." He said, "I like to take my share of the labor."