Ibn 'Umar rep rte that Allah's Messenger (ﷺ) combined the sunset and 'Isha ' prayers at Muzdalifa. He observed three rak'ahs of the sunset prayer and two rak'ahs of the 'Isha' prayer with one Iqama.
Sahih Muslim Book 15, Hadith 318
← Previous Hadith He (the Holy Prophet) observed the two prayers (together) with one iqama.

Sahih Muslim Book 15, Hadith 317 Next Hadith → We came back along with Ibn 'Umar till we reached Muzdalifa. There he led us in the sunset and 'Isha' prayers with one iqama and we then proceeded and he said: This is how Allah's Messenger (ﷺ) led us in prayer at this place.

Sahih Muslim Book 15, Hadith 319