Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) narrates: At the time of Hajj, the Prophet (peace and blessings be upon him) used to go to the tribes one by one and invite them, until Allah Almighty brought this group of the Ansar, when Allah Almighty decreed good fortune for them and brought honor to them. They promised to shelter him and also promised to help him, so may Allah Almighty reward them with good on behalf of their Prophet. By Allah, we did not fulfil what we had agreed with them as it should be. We used to say to them: "We will be the rulers and you will be the ministers." If I remain alive for a year, no ghulam of mine will remain, except that the case of an Ansari is different.
Al-Bazzar recorded it, and its chain is hasan (good); its chain contains a narrator, Abdullah bin Shabib, who is da'if (weak).