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. (Using translation from Muslim 1288d)
أَنَّ النَّبِيَّ ﷺ جَمَعَ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ صَلَّى الْمَغْرِبَ ثَلَاثًا وَالْعِشَاءَ رَكْعَتَيْنِ بِإِقَامَةٍ وَاحِدَةٍ