(47) باب الإِفَاضَةِ مِنْ عَرَفَاتٍ إِلَى الْمُزْدَلِفَةِ وَاسْتِحْبَابِ صَلاَتَىِ الْمَغْرِبِ وَالْعِشَاءِ جَمْعًا بِالْمُزْدَلِفَةِ فِي هَذِهِ اللَّيْلَةِ
Sa'id b. Jubair reported that he observed the sunset and 'Isha' prayers at Muzdalifa with (one) iqama. He narrated on the authority of Ibn 'Umar (Allah be pleased with them) that he observed prayers like this and Ibn 'Umar (Allah be pleased with them) narrated that Allah's Apostle (ﷺ) did like this.
Reference: Sahih Muslim 1288 b
In-book reference: Book 15, Hadith 316
USC-MSA web (English) reference(deprecated numbering scheme): Book 7, Hadith 2953