Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 2952
Ubaidullah b. 'Abdullah b. 'Umar reported on the authority of his father (Allah be pleased with them) that Allah's Messenger (may peace be upon him) 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.