Musannaf Ibn Abi Shayba 18:1244

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Khalifah ibn Khayyat, from ‘Amr ibn Shu’ayb, from his father, from his grandfather, from the Prophet, may Allah bless him and grant him peace, that he said in his sermon while his back was leaning against the Ka’bah: "The blood of the Muslims is equal in value. The lowest of them strives for their protection, and they are a united hand against those who are other than them."