Sayyiduna Urwah bin Mudarris (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah! I am exhausted, I have endured hardship, and my feet are worn from walking." The Messenger of Allah (peace and blessings be upon him) said: "Whoever reaches Muzdalifah with the people and the imam before they depart has caught the Hajj; and whoever does not find the people and the imam at Muzdalifah before they depart has not caught the Hajj."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14455