Musannaf Ibn Abi Shayba 19:867

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Abu Salih, the freed slave of al-Taw’ama, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "I have been commanded to fight the people until they say: 'There is no god but Allah.' So if they say it, their blood and their wealth are forbidden to me, except by its right, and their reckoning is with Allah."