BURNING TO DEATH Is strictly forbidden by Muslim law. ‘Ikrimah relates that some apostates from Islam were brought to the Khalifah ‘Ali, and he burnt them; and when Ibn ‘Abbas heard of it, he said, “Had they been brought to me, I would not have burnt them; for the Prophet said, ‘Punish not with God’s punishment. Verily it is not fit for anyone to punish with fire but God.’ (Mishkat, c.v. part 1.)
Based on Hughes, Dictionary of Islam