It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that one day the Messenger of Allah (peace and blessings be upon him) said: "Who will pledge allegiance?" Sayyiduna Thawban (may Allah be pleased with him), the freed slave of the Messenger of Allah (peace and blessings be upon him), said: On what shall we pledge allegiance? Have we not already pledged allegiance to you once, O Messenger of Allah? He said: "That you will not ask anyone for anything." Sayyiduna Thawban said: What will he get in return for it, O Messenger of Allah? He said: "Paradise." So Sayyiduna Thawban (may Allah be pleased with him) pledged allegiance. Sayyiduna Abu Umamah (may Allah be pleased with him) said: I saw him in Makkah amid the crowds of people, riding, when his whip would fall, and sometimes it would land on a man's shoulder. That man would pick it up and hold it out to him, but he would not take it; rather, he would dismount himself and pick it up.
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7801