Silsilat al-Ahadith al-Sahihah

Sayyiduna Abu Musa (may Allah be pleased with him) says: The Messenger of Allah (peace and blessings of Allah be upon him) came to the door of a house in which some Quraysh were sitting. He held the door frame and stood, and asked: "Are there only Quraysh in the house?" It was said: O Messenger of Allah! (We are all Quraysh, except) our nephew is also present. He (peace and blessings of Allah be upon him) said: "A people's nephew is considered one of them." Then he said: "This (matter of leadership) will remain among the Quraysh as long as they show mercy when mercy is requested, judge with justice, and are fair in distribution. Whoever does not do so, upon him is the curse of Allah, the angels, and all people. Neither his obligatory worship will be accepted nor his voluntary."