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  

"The Messenger of Allah joined Maghrib and Isha with no (Voluntary) prayer in between them. He prayed Maghrib with three Rakahs and Isha with two." And Abdullah bin Umar used to join them in like manner until he met Allahm, The Mighty and Sublime.  

جَمَعَ رَسُولُ اللَّهِ ﷺ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ لَيْسَ بَيْنَهُمَا سَجْدَةٌ صَلَّى الْمَغْرِبَ ثَلاَثَ رَكَعَاتٍ وَالْعِشَاءَ رَكْعَتَيْنِ وَكَانَ عَبْدُ اللَّهِ بْنُ عُمَرَ يَجْمَعُ كَذَلِكَ حَتَّى لَحِقَ بِاللَّهِ ﷻ  

[Machine] The Messenger of Allah ﷺ combined the Maghrib and Isha prayers without a separate prostration between them. He prayed three rak'ahs for Maghrib and two rak'ahs for Isha. Abdullah continued to pray in this manner until he joined Allah.  

جَمَعَ رَسُولُ اللهِ ﷺ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ لَيْسَ بَيْنَهُمَا سَجْدَةٌ وَصَلَّى الْمَغْرِبَ ثَلَاثَ رَكَعَاتٍ وَصَلَّى الْعِشَاءَ رَكْعَتَيْنِ فَكَانَ عَبْدُ اللهِ يُصَلِّي بِجَمْعٍ كَذَلِكَ حَتَّى لَحِقَ بِاللهِ ﷻ