كتاب الحج
15  
The Book of Pilgrimage
(47)
Chapter: Departing from 'Arafat to Al-Muzdalifah. It is recommended to pray Maghrib and 'Isha together in Al-Muzdalifah on this night
(47)
باب الإِفَاضَةِ مِنْ عَرَفَاتٍ إِلَى الْمُزْدَلِفَةِ وَاسْتِحْبَابِ صَلاَتَىِ الْمَغْرِبِ وَالْعِشَاءِ جَمْعًا بِالْمُزْدَلِفَةِ فِي هَذِهِ اللَّيْلَةِ
Sahih Muslim 1280 b

Kuraib, the freed slave of Ibn Abbas, narrated from Usama b. Zaid (Allah be pleased with him) that he had heard him saying:

Allah's Messenger (ﷺ) proceeded from 'Arafa, and as he approached the creek of a hill, he got down (from his camel) and urinated, and then performed a light ablution. I said to him: Prayer, whereupon he said: The prayer awaits you (at Muzdalifa). So he rode again, and as he came to Muzdalifa, he got down and performed ablution well. Then Iqima was pronounced for prayer, and he 'observed the sunset prayer. Then every person made his camel kneel down there, and then Iqama was pronounced for 'Isha' prayer and he observed it, and he (the Holy Prophet) did not observe any prayer (either Sunan or Nawifil) in between them (He observed the Fard of sunset and 'Isha' prayers successively.)
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ مُوسَى بْنِ عُقْبَةَ، عَنْ كُرَيْبٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنْ أُسَامَةَ بْنِ زَيْدٍ، أَنَّهُ سَمِعَهُ يَقُولُ دَفَعَ رَسُولُ اللَّهِ صلى الله عليه وسلم مِنْ عَرَفَةَ حَتَّى إِذَا كَانَ بِالشِّعْبِ نَزَلَ فَبَالَ ثُمَّ تَوَضَّأَ وَلَمْ يُسْبِغِ الْوُضُوءَ فَقُلْتُ لَهُ الصَّلاَةَ ‏.‏ قَالَ ‏ "‏ الصَّلاَةُ أَمَامَكَ ‏"‏ ‏.‏ فَرَكِبَ فَلَمَّا جَاءَ الْمُزْدَلِفَةَ نَزَلَ فَتَوَضَّأَ فَأَسْبَغَ الْوُضُوءَ ثُمَّ أُقِيمَتِ الصَّلاَةُ فَصَلَّى الْمَغْرِبَ ثُمَّ أَنَاخَ كُلُّ إِنْسَانٍ بَعِيرَهُ فِي مَنْزِلِهِ ثُمَّ أُقِيمَتِ الْعِشَاءُ فَصَلاَّهَا وَلَمْ يُصَلِّ بَيْنَهُمَا شَيْئًا.
Reference : Sahih Muslim 1280b
In-book reference : Book 15, Hadith 304
USC-MSA web (English) reference : Book 7, Hadith 2941
  (deprecated numbering scheme)