Musannaf Ibn Abi Shaybah

Hazrat Amir (may Allah be pleased with him) narrates that Hazrat Anas bin Malik (may Allah be pleased with him) said: Some people from the tribe of Bakr bin Wa'il apostatized from Islam and joined the polytheists. Then they were killed in battle. When I brought the news of the conquest of Tustar to Hazrat Umar bin Khattab (may Allah be pleased with him), he asked: What happened to the people of the tribe of Bakr bin Wa'il? The narrator says that I started another topic in front of him so that I could divert him from mentioning them, but he asked again: What happened to the group of Bakr bin Wa'il? I replied, O Commander of the Faithful! They were killed. He said: If I had made a peace agreement with them, that would have been more beloved to me than the gold and silver upon which the sun rises. The narrator says: I said, O Commander of the Faithful! If you had captured those people who apostatized from Islam and joined the polytheists, what other way could there have been except to kill them? He replied: I would have presented to them that they enter through the same door from which they exited; if they did so, I would have accepted these things from them, and if they refused to do so, I would have imprisoned them in jails.