From Sahih Muslim (Hadith 3111):
Ubaidullah b. 'Abdullah b. 'Umar reported on the authority of his father (Allah be pleased with them) that Allah's Messenger (ﷺ) combined the sunset and 'Isha', prayers at Muzdalifa and there was no prostration (i. e. any rak'ahs of Sunan or Nawafil prayers) in between them. He observed three rak'ahs of the sunset prayer and two rak'ahs of the 'Isha' prayer, and 'Abdullah (b. 'Umar) observed the prayers in this very manner (at Muzdalifa) until he met his Lord
Reference: Muslim 3111