Musnad Ahmad 643:2

Rawh narrated to us, Shu'bah narrated to us, he said: I heard 'Abdullah ibn Abi al-Safar, he said: I heard al-Sha'bi, from 'Urwah ibn Mudarris ibn Harithah ibn Lam, he said: I came to the Messenger of Allah, may Allah bless him and grant him peace, while he was at Jam' (Muzdalifah), and I said to him: "Is there a Hajj for me?" He said: "Whoever prays this prayer with us in this place, then stands with us at this station until the Imam departs—having departed from 'Arafat before that, by night or by day—then his Hajj is complete, and he has fulfilled his rites."