It is narrated from Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) conquered Makkah, then he (peace and blessings be upon him) set out towards Ta'if and besieged them for seven or eight days. Then he (peace and blessings be upon him) advanced in the morning or the evening, then halted and spent the midday there. Then he said: "O people, I am your forerunner (at the Pond), and I enjoin you to treat my family ('itrah, the People of the House) well. Your appointment with me is at the Pond (al-Kawthar). By the One in whose hand is my soul, you shall surely establish the prayer and pay the zakah, or else I will send against you a man who is from me (or he said: who is like my own self), who will strike the necks of their fighters and take their offspring captive." The narrator says: The people thought that he (peace and blessings be upon him) meant Abu Bakr or Umar (may Allah be pleased with them both), but he (peace and blessings be upon him) took hold of the hand of Ali (may Allah be pleased with him) and said: "This is the man." This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.