Musnad Ahmad 262:2

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed us, he said: Ziyad—meaning Ibn Sa'd—informed me that Abu al-Zinad said: Hanzalah ibn 'Ali informed me, from Hamzah ibn 'Amr al-Aslami, a companion of the Prophet, may Allah bless him and grant him peace, that he narrated to him: That the Messenger of Allah, may Allah bless him and grant him peace, sent him and a group with him to a man from 'Udhrah, and he said: "If you are able to capture so-and-so, then burn him with fire." They departed, and when they were hidden from him, he called them—or sent someone after them—and they returned to him. Then he said: "If you are able to capture him, then kill him, and do not burn him with fire, for none punishes with fire except the Lord of the fire."