Musnad Ahmad 25:1395

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from Ayyub, from 'Ikrimah, from Ibn 'Abbas, who said—and I do not know it except that he attributed the hadith [to the Prophet]—he said: "He used to command the killing of snakes, and he would say: 'Whoever leaves them out of fear or apprehension of their retaliation, then he is not of us.'" Ibn 'Abbas said: "Indeed, the Jinn are the deformed ones of the Jinn, just as the monkeys were deformed from the Children of Israel."