Musannaf Ibn Abi Shaybah

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.