Sahih Muslim , Book 7, Hadith 2951 (USC-MSA) ⓘ
Ibn Umar (Allah be pleased with them) reported that Allah's Messenger observed the sunset and 'Isha' prayers together at Muzdalifa.
وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ، عَبْدِ اللَّهِ عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى الْمَغْرِبَ وَالْعِشَاءَ بِالْمُزْدَلِفَةِ جَمِيعًا .
also referenced under: Book 15, Hadith 314 (In-Book) & Hadith 703 (Reference)