The Book of Pilgrimage
15/47. Chapter:
Departing from 'Arafat to Al-Muzdalifah. It is recommended to pray Maghrib and 'Isha together in Al-Muzdalifah on this night
Sahih Muslim
وَحَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَنَّأَخْبَرَهُ أَنَّ أَبَاهُ قَالَ جَمَعَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ لَيْسَ بَيْنَهُمَا سَجْدَةٌ وَصَلَّى الْمَغْرِبَ ثَلاَثَ رَكَعَاتٍ وَصَلَّى الْعِشَاءَ رَكْعَتَيْنِ . فَكَانَ عَبْدُ اللَّهِ يُصَلِّي بِجَمْعٍ كَذَلِكَ حَتَّى لَحِقَ بِاللَّهِ تَعَالَى .
Ubaidullah b. 'Abdullah b. 'Umar reported on the authority of his father (Allah be pleased with them) that Allah's Messenger (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.
Reference : Sahih Muslim 1288aIn-book reference : Book 15, Hadith 315USC-MSA web (English) reference : Book 7, Hadith 2952