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

Usama b. Zaid (Allah be pleased with him) reported:

Allah's Messenger (ﷺ) on his way back from 'Arafat got down in one of these creeks (to answer the call of nature), and after he had done that I poured water (over his hands) and said: Are you going to pray? Thereupon he said: The place of prayer is ahead of you.
وَحَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَخْبَرَنَا اللَّيْثُ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ مُوسَى بْنِ عُقْبَةَ، مَوْلَى الزُّبَيْرِ عَنْ كُرَيْبٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنْ أُسَامَةَ بْنِ زَيْدٍ، قَالَ انْصَرَفَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَعْدَ الدَّفْعَةِ مِنْ عَرَفَاتٍ إِلَى بَعْضِ تِلْكَ الشِّعَابِ لِحَاجَتِهِ فَصَبَبْتُ عَلَيْهِ مِنَ الْمَاءِ فَقُلْتُ أَتُصَلِّي فَقَالَ ‏ "‏ الْمُصَلَّى أَمَامَكَ ‏"‏ ‏.‏
Reference : Sahih Muslim 1280 c
In-book reference : Book 15, Hadith 305
USC-MSA web (English) reference : Book 7, Hadith 2942
  (deprecated numbering scheme)