Sayyiduna Aws (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) came to us while we were in a tent in the mosque of Madinah, and he (peace and blessings be upon him) took hold of part of the tent. Then a man came and whispered something to him, and it could not be known what he was saying. He (peace and blessings be upon him) said: "Go and tell them to kill him." Then he said: "Perhaps he bears witness that there is no deity except Allah (la ilaha illallah)?" He said: Yes. He (peace and blessings be upon him) said: "Go and tell them to release him, for I have been commanded to fight the people until they say: la ilaha illallah. Then when they say it, their blood and their wealth become inviolable for me, except for a rightful matter, and their reckoning is with Allah, the Mighty and Majestic."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 589