Sayyiduna Anas bin Malik (may Allah be pleased with him) says: On the day of Tustar, six people from Banu Bakr bin Wa'il became apostates. I went to Umar bin Khattab (may Allah be pleased with him). He asked: "What happened to those people?" I turned the conversation to something else. Then he asked again. I said: "They were killed." Umar (may Allah be pleased with him) said: "If I had found them, it would have been more beloved to me than the rising of the sun." I said: "Was it necessary to kill them?" He said: "I would have called them back to Islam; if they accepted, fine, otherwise I would have put them in prison."