Musannaf Ibn Abi Shaybah

Hazrat Abdur Rahman narrates that when the news of the conquest of Tustar reached Hazrat Umar—Tustar is the name of a region in Basra—he asked those people: "Is there any other news from a distant place?" They said: "A Muslim man had joined the polytheists, so we captured him." He asked: "What did you do with him?" They said: "We killed him." He said: "Why did you not take him into a house and lock the door on him, and give him one chapati to eat each day, then ask him to repent three times? If he repented, then fine; otherwise, you could have killed him!" Then he said: "O Allah! I was not present, nor did I order it, nor was I pleased with it when the news reached me."