Musannaf Ibn Abi Shaybah 30950 — Heretics (zanadiqah): what

Sayyiduna Mukhariq (may Allah be pleased with him) says that Sayyiduna Ali (may Allah be pleased with him) sent Muhammad bin Abi Bakr as governor over Egypt. Muhammad then wrote to Sayyiduna Ali (may Allah be pleased with him), asking him about the zindiqs: "Some of them worship the sun and the moon, some of them worship other things, and some of them claim Islam. What is the ruling concerning them?" Sayyiduna Ali (may Allah be pleased with him) wrote back and commanded him concerning the zindiqs that he should kill those who claim Islam and leave all the rest to worship whatever they wish.