Thus originated the practice, passed down to today, of Friday worship. The Muslim calendar Year 1 is equivalent to the year 622 in the Christian calendar. Because Mohammed did not designate a successor, after his death there was a succession problem.
由於穆罕默德並未指定繼承人，他所建立的回教王國，在他過世後不久，就起了繼承者之爭，造成後世的兄弟鬩牆和派別問題。