Musnad Abu Ya'la al-Mawsili 209:38

Shayban narrated to us, al-Qasim ibn al-Fadl al-Haddani narrated to us, Muhammad ibn Ali narrated to us, he said: Umm Salamah used to say: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Hajj is the jihad of every weak person."