Ibn 'Umar rep rte that Messenger of Allah ﷺ combined the sunset and 'Isha ' prayers at Muzdalifa. He observed three rak'ahs of the sunset prayer and two rak'ahs of the 'Isha' prayer with one Iqama.
جَمَعَ رَسُولُ اللَّهِ ﷺ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ صَلَّى الْمَغْرِبَ ثَلاَثًا وَالْعِشَاءَ رَكْعَتَيْنِ بِإِقَامَةٍ وَاحِدَةٍ