Musnad Ahmad 1153:1570

Waki’ narrated to us, Hisham narrated to us, the like of it. Waki’ said: "And perform ghusl (ritual bath) and enter into the state of ihram for Hajj." ‘Urwah said: "So Allah, the Almighty and Majestic, decreed her Hajj and her ‘Umrah."