Musannaf Ibn Abi Shaybah

Hazrat Ibn Ubaid bin Abrasi narrates that a man was brought to Hazrat Ali (may Allah be pleased with him), son of Abu Talib, who was a Christian. Then he accepted Islam, and then he adopted Christianity again. The narrator says that Hazrat Ali (may Allah be pleased with him) asked him about this matter, and he informed him. So Hazrat Ali (may Allah be pleased with him) stood up towards him and kicked him on his chest, and the people also stood up and began to beat him until they killed him.

Hazrat Abu al-Tufail narrates: I was in the army which Hazrat Ali (may Allah be pleased with him) ibn Abi Talib sent towards Banu Najiyah. He says: When we reached them, we found those people in three groups. Our commander asked one of the groups: What is your situation? They said: We were Christians and did not consider any religion better than our own, so we remained steadfast upon it. Upon this, the commander said: Separate yourselves. Then he asked another group: What is your situation? They said: We were Christians, then we accepted Islam and remained steadfast upon Islam. So the commander said: You also separate yourselves. Then the commander asked the third group: What is your situation? They said: We were Christians, then we accepted Islam, then we turned back. We did not consider any religion better than our first religion, so we adopted Christianity. So the commander said to them: Accept Islam. Those people refused, so the commander said to his companions: When I pass my hand over my head three times, attack them. So they did so, killed those who fought, and took their children captive.

Hazrat Tawus narrates that Hazrat Ibn Abbas (may Allah be pleased with them) said: Do not let Jews and Christians stay with you in one place unless they accept Islam. So, if any of them accepts Islam and then becomes an apostate, do not kill him except by striking his neck.