The Messenger of allah said: "Whoever catches up (with Fajir prayer) in Jam (Al-Muzdalifah) with the Imam and the people (and stays there) until they move on, the he has caught up with Hajj. Whoever does not catuch up with the people and the Imam, then has not caught it (Hajj).'" (Using translation from Nasāʾī 3040)
قَالَ رَسُولُ اللهِ ﷺ «مَنْ أَدْرَكَ جَمْعًا مَعَ الْإِمَامِ وَالنَّاسِ حَتَّى يُفِيضُوا فَقَدْ أَدْرَكَ الْحَجَّ وَمَنْ لَمْ يُدْرِكْ مَعَ النَّاسِ وَالْإِمَامِ فَلَمْ يُدْرِكْ»