Musannaf Ibn Abi Shayba 28:569

Hafs ibn Ghiyath narrated to us, from al-A'mash, from Abu Sufyan, from Jabir, and from Abu Salih, 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.' If they say it, they have protected their wealth and their blood by it, and their reckoning is with Allah."