Narrated Usama bin Zaid:

"When Allah's Apostle departed from 'Arafat, he turned towards a mountain pass where he answered the call of nature. (After he had finished) I poured water and he performed ablution and then I said to him, "O Allah's Apostle! Will you offer the prayer?" He replied, "The Musalla (place of the prayer) is ahead of you (in Al-Muzdalifa)."

حَدَّثَنِي مُحَمَّدُ بْنُ سَلاَمٍ، قَالَ أَخْبَرَنَا يَزِيدُ بْنُ هَارُونَ، عَنْ يَحْيَى، عَنْ مُوسَى بْنِ عُقْبَةَ، عَنْ كُرَيْبٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنْ أُسَامَةَ بْنِ زَيْدٍ، أَنَّ رَسُولَ اللَّهِ ﷺ لَمَّا أَفَاضَ مِنْ عَرَفَةَ عَدَلَ إِلَى الشِّعْبِ، فَقَضَى حَاجَتَهُ. قَالَ أُسَامَةُ بْنُ زَيْدٍ فَجَعَلْتُ أَصُبُّ عَلَيْهِ وَيَتَوَضَّأُ فَقُلْتُ يَا رَسُولَ اللَّهِ أَتُصَلِّي فَقَالَ " الْمُصَلَّى أَمَامَكَ ".