Majma al-Zawaid — Hadith 13664

Ubaydullah bin Ziyad al-Hadrami narrates: Once Malik bin Dinar met Salim bin Abdullah bin Umar bin al-Khattab, who at that time was riding a donkey whose ears were drooping; its saddle was in poor condition, and his clothes were shabby too. Salim asked him: "Where are you from?" He told him: "From you people, and from some of your mawali (clients)." Then he said: "My father narrated this hadith to me from the Prophet (peace and blessings be upon him); he (peace and blessings be upon him) said: 'A Muslim is the brother of a Muslim; he does not let him be disgraced, he does not betray him, and he does not abandon him in any calamity that befalls him. If the best of the Arabs and the mawali perish while they love one another, they will have no escape from that; and if the worst of the two groups perish because of hating one another, they will have no escape from that.'"
Al-Tabarani recorded it, and its chain is jayyid (good).