I saw the Messenger of Allah ﷺ standing at Muzdalifa, and he said, "Whoever prays this prayer of ours here with us and then stays with us, having already stood at Arafah before that, by night or by day, his pilgrimage is complete."
أخبرنا سعيد بن عبد الرحمن قال حدثنا سفيان عن إسمعيل وداود وزكريا عن الشعبي
رأيت رسول الله ﷺ واقفا بالمزدلفة فقال من صلى معنا صلاتنا هذه ها هنا ثم أقام معنا وقد وقف قبل ذلك بعرفة ليلا أو نهارا فقد تم حجه
Sourcing, sahih. Reported by Tirmidhi in the book of Hajj, chapter on whoever catches up with the imam at Jam, has caught up with Hajj, hadith no. 891, from the hadith of Sufyan bin Uyayna, with this chain, and he said, hasan sahih. Ibn Khuzayma graded it sahih, 4/256, hadith no. 2821, as did Ibn Hibban, hadith no. 1010, and Hakim, 1/463, and Dhahabi.Saeed bin Abdul-Rahman, 2821, is Ibn Hassan the Qurashi, Abu Ubaydullah the Makhzumi, the Makkan. Ismail is Ibn Abu Khalid. Dawud is Ibn Abu Hind. Zakariya is Ibn Abu Zaida.