It was narrated that Urwah said: "Ibn 'Umar was asked· 'In which month did the 'Messenger of Allah P.B.U.H perform Ummrah?' He said: 'In Rajab.' But Aishah said: The Messenger of Allah P.B.U.H never performed 'Umrah during Rajah, and he never performed 'Umrah, but he (meaning Ibn 'Umar) was with him." (Sahih)