Musannaf Ibn Abi Shayba 28:861

'Abd al-Rahim ibn Sulayman narrated to us, from al-Walid ibn Abi Malik, from al-Qasim ibn 'Abd al-Rahman, from Abu Umamah, from the Prophet (peace be upon him), who said: "The protection granted by any one of them [the Muslims] is binding upon all the Muslims."