Musannaf Ibn Abi Shayba 19:567

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Muhammad bin Muslim, from Ibrahim bin Maysara, he said: Al-Rida—meaning Tawus—narrated to me, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever mutilates with hair is not of us."