Sahih Muslim Book 20, Hadith Number 4548.

Chapter : Fulfilment of the covenant made with the Caliphs is imperative, the caliph to whom allegiance is sworn in the first instance has an established supremacy over those who assume powers.

It has been narrated on the authority of ‘Abd Rabb al-Ka’ba as-Sa’idl who said: I saw a group of people near the Ka’ba… Then he narrated the tradition as narrated by A’mash.