Ikrimah (may Allah have mercy on him) says that once Sayyiduna Ali (may Allah be pleased with him) burned some apostates. When Sayyiduna Ibn Abbas (may Allah be pleased with them both) found out, he said: If I had been there, I would not have burned them with fire, because the Prophet (peace and blessings of Allah be upon him) said: "Do not punish anyone with the punishment of Allah." Rather, I would have killed them, because the Prophet (peace and blessings of Allah be upon him) said: "Whoever changes his religion, kill him." When Sayyiduna Ali (may Allah be pleased with him) learned of this, he expressed regret (that why was this not known earlier?).