Usama bin Zayd reported,

When the Messenger of Allah ﷺ departed from Arafah, he turned aside into a mountain pass and relieved himself.Usama bin Zayd said, "I began pouring water for him while he performed ablution."I asked, "Messenger of Allah, will you pray now?"He replied, "The place of prayer is ahead of you."

Azami 5133

Sahih

عن أسامة بن زيد

أن رسول الله ﷺ لما أفاض من عرفة عدل إلى الشعب، فقضى حاجته. قال أسامة بن زيد: فجعلت أصب عليه ويتوضأ. فقلت يا رسول الله، أتصلي؟ فقال: المصلى أمامك.

الأعظمي 5133صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Hajj
Chapter
Description of the Hajj of the Prophet ﷺ as narrated by Jabir and others, and the rulings mentioned therein
Section
Combining the two prayers at Muzdalifa
Numbering
Jami al-Kamil 5133 (2nd edition)
Azami 5133