[Abdullah] Ibn 'Umar narrated that the Messenger of Allah (s.a.w) said:"Three shall be on dunes of musk" - it seems to me that he said:- "on the Day of Resurrection. The first and the last of peoples shall envy them: A man who calls to the five [prayers] every day and night; a man who leads a group of people and they are pleased with him, and a slave who fulfills the right of Allah and the right of his masters