Muhammad bin Ishaq bin Yasar reports the sermon of Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him), in which he said: "This matter (leadership) belongs to Quraysh as long as they obey Allah and remain steadfast upon His command; this has reached you, or you have heard it, from the Messenger of Allah (peace and blessings be upon him). 'And do not dispute with one another, lest you lose courage and your strength departs; and be patient. Indeed, Allah is with the patient.' [Surah al-Anfal: 46] So we are the leaders and you are the ministers; you are our brothers in religion and our helpers upon it." Then in his sermon after him, Sayyiduna Umar (may Allah be pleased with him) said: "I adjure you by Allah, O Ansar! Did you not hear the Messenger of Allah (peace and blessings be upon him), or did not those of you who heard him, (hear him) say: 'The rulers are from Quraysh as long as they obey Allah and remain steadfast upon His command'?" Some of the Ansar said: "Yes, now we remember." He said: "Then we seek this matter only for this (reason), so do not let desires lead you astray, for after the truth there is nothing but misguidance; so how are you being turned away?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16537