Musnad Ahmad 33:535

Aswad narrated to us, Sharik narrated to us, from Abdullah ibn Muhammad ibn Aqil, from Jabir, who attributed the hadith [to the Prophet], he said: "I have been commanded to fight the people until they say: 'There is no god but Allah.' If they say it, their blood and their wealth become inviolable to me, and their reckoning is with Allah," or "their reckoning is upon Allah."