The Messenger of Allah ﷺ appointed him as commander of a military expedition. He said, "I set out with the expedition, and he had said, 'If you find so-and-so, burn him with fire.'" As he was leaving, the Messenger of Allah ﷺ called him back, so he returned to him.The Prophet ﷺ said, "If you find so-and-so, kill him but do not burn him, for none punishes with fire except the Lord of fire."
حدثنا سعيد بن منصور حدثنا مغيرة بن عبد الرحمن الحزامي عن أبي الزناد
أن رسول الله ﷺ أمره على سرية قال فخرجت فيها وقال إن وجدتم فلانا فأحرقوه بالنار فوليت فناداني فرجعت إليه فقال إن وجدتم فلانا فاقتلوه ولا تحرقوه فإنه لا يعذب بالنار إلا رب النار
[Its isnad is hasan] Ahmad narrated it, 3/494, from Saeed bin Mansur, with the same wording, and it is found in his Sunan, hadith no. 2643, with a slight difference, and Hafiz declared it sahih in Fath al-Bari, 6/149.