From Sahih Muslim (Hadith 3116):
A'bdullah (b. 'Umar) reported:I have never seen Allah's Messenger, (ﷺ) but observing the prayers at their appointed times except two prayers, sunset and 'Isha, ' at Muzdalifa (where he deferred the sunset prayer to combine it with 'Isha' and he observed the dawn prayer before its stipulated time on that day (10th of Dhu'l-Hijja)
Reference: Muslim 3116