Ali was brought some people from the Zutt who were worshipping an idol, so he burned them. Ibn Abbas said, "The Messenger of Allah ﷺ only said, 'Whoever changes his religion, kill him.'"
أخبرنا محمد بن المثنى قال حدثنا عبد الصمد قال حدثنا هشام عن قتادة
أن عليا أتي بناس من الزط يعبدون وثنا فأحرقهم قال ابن عباس إنما قال رسول الله ﷺ من بدل دينه فاقتلوه
[Sahih]. Ahmad narrated it from Abdul-Samad through him. See (the previous hadith). It is also in Kubra, hadith no. 3528.