Ubaidullah b. 'Abdullah b. 'Umar reported on the authority of his father (Allah be pleased with them) that Messenger of Allah ﷺ combined the sunset and 'Isha', prayers at Muzdalifa and there was no prostration (i. e. any rak'ahs of Sunan or Nawafil prayers) in between them. He observed three rak'ahs of the sunset prayer and two rak'ahs of the 'Isha' prayer, and 'Abdullah (b. 'Umar) observed the prayers in this very manner (at Muzdalifa) until he met his Lord.
جَمَعَ رَسُولُ اللَّهِ ﷺ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ لَيْسَ بَيْنَهُمَا سَجْدَةٌ وَصَلَّى الْمَغْرِبَ ثَلاَثَ رَكَعَاتٍ وَصَلَّى الْعِشَاءَ رَكْعَتَيْنِ فَكَانَ عَبْدُ اللَّهِ يُصَلِّي بِجَمْعٍ كَذَلِكَ حَتَّى لَحِقَ بِاللَّهِ تَعَالَى