Ikrima reported,

Ali was brought a group of these heretics who had books with them. He ordered a fire to be kindled, and once it was blazing, he burned them along with their books.Ikrima said, "When this reached Ibn Abbas, he said, 'Had it been me, I would not have burned them, because of the prohibition of the Messenger of Allah ﷺ. But I would have killed them, because of the saying of the Messenger of Allah ﷺ, "Whoever changes his religion, kill him." And the Messenger of Allah ﷺ said, "Do not punish with the punishment of Allah ."'"

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عن عكرمة

أن عليا رضي الله عنه أتي بقوم من هؤلاء الزنادقة ومعهم كتب فأمر بنار فأججت ثم أحرقهم وكتبهم قال عكرمة فبلغ ذلك ابن عباس فقال لو كنت أنا لم أحرقهم لنهي رسول الله ﷺ ولقتلتهم لقول رسول الله ﷺ من بدل دينه فاقتلوه وقال رسول الله ﷺ لا تعذبوا بعذاب الله عز وجل