Sufyan says: I saw Amr bin Dinar, Ayyub and Ammar al-Duhni gathered together, and they discussed those whom Ali (may Allah be pleased with him) had burned.
(b) Ikrimah narrates from Abdullah bin Abbas (may Allah be pleased with them both): Had it been me, I would not have burned them, because of the saying of the Messenger of Allah (peace and blessings be upon him): "Do not punish with the punishment of Allah," and I would have killed them because of the saying of the Messenger of Allah (peace and blessings be upon him): "Whoever apostatises (changes his religion), kill him." Ammar says: They were not burned; rather, pits were dug for them, with holes made (between them) inside, then smoke was let in upon them until they died. Amr said: The poet has said: Cast me before death however you wish, so long as you have not cast me into the two pits when they have gathered firewood and fire; then death comes at once and does not delay.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18062
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) sent us out in an expedition. He (peace and blessings be upon him) said: "If you find two particular men of the Quraysh, burn them with fire." Then when we were about to leave, the Messenger of Allah (peace and blessings be upon him) said: "I had ordered you to burn so-and-so and so-and-so with fire, but none punishes with fire except Allah, the Lord of Might. If you find them, kill them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18063
It is narrated from Sayyiduna Hamzah bin Amr al-Aslami (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) sent a man (saying): "If you find so-and-so and so-and-so, burn them with fire." When he was about to leave, he (peace and blessings be upon him) called him back and said: "None may punish with fire except the Lord of the fire."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18064
Muhammad bin Hamzah al-Aslami (may Allah be pleased with him) narrates from his father (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) made him the commander of a detachment. He says: I went out with that detachment. He (peace and blessings be upon him) said: "If you find so-and-so, burn him with fire." As I was leaving, he (peace and blessings be upon him) called out to me. When I came back, he (peace and blessings be upon him) said: "If you find so-and-so, kill him, but do not burn him; for none may punish with fire except its Lord."
(b) The hadith of Usamah bin Zayd (may Allah be pleased with them both), in which the Messenger of Allah (peace and blessings be upon him) ordered him to burn Ubna (a settlement), and what is narrated about setting up the catapult against Ta'if, do not contradict what we have said. That concerns only fighting the polytheists while they are resisting (and beyond control), whereas the prohibition (of punishing with fire) concerning the polytheists applies when they are captives.
Imam al-Shafi'i (may Allah have mercy on him) likened this to shooting game while it is beyond control, and then the prohibition of shooting a hen that is not beyond control (that is, one that is tied up).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18065