It was narrated that Sa'eed bin Jubair said:
"I was with Ibn 'Umar when he departed from 'Arafah. When he came to Jam' (Al-Muzdalifah), he combined Maghrib and 'Isha', and when he finished he said: 'The Messenger of Allah (ﷺ) did similar to this in this place.'" (ES)
English reference (ES): Vol. 1, Book 6, Hadith 607 (ES)
Arabic reference (ES): Book 6, Hadith 613 (ES)