Sayyiduna Abu Dharr al-Ghifari (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) took a pledge of allegiance from me regarding five things, took a firm covenant from me regarding seven things, and made Allah Almighty a witness over me regarding nine things: that I would not care about the blame of any blamer concerning Allah Almighty. Abu al-Muthanna narrates: Sayyiduna Abu Dharr al-Ghifari (may Allah be pleased with him) said: The Prophet (peace and blessings be upon him) called me and said: "Would you like to give the pledge of allegiance? You will have Paradise." I said: "Yes!" Then I stretched out my hand, and the Prophet (peace and blessings be upon him), laying down a condition for me, said that I must never ask people for anything. I said: "All right." The Prophet (peace and blessings be upon him) said: "Not even if your whip falls; you will not ask for it either, but will get down yourself and pick it up."
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الزكاة / 4503