Sahih Muslim , Book 7, Hadith 2953 (USC-MSA) ⓘ

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 did like this.

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، وَسَلَمَةَ بْنِ كُهَيْلٍ عَنْ سَعِيدِ بْنِ جُبَيْرٍ، أَنَّهُ صَلَّى الْمَغْرِبَ بِجَمْعٍ وَالْعِشَاءَ بِإِقَامَةٍ ثُمَّ حَدَّثَ عَنِ ابْنِ عُمَرَ أَنَّهُ صَلَّى مِثْلَ ذَلِكَ وَحَدَّثَ ابْنُ عُمَرَ أَنَّ النَّبِيَّ صلى الله عليه وسلم صَنَعَ مِثْلَ ذَلِكَ ‏.‏

Shu'ba reported this hadith with the same chain of transmitters and said: He (the Holy Prophet) observed the two prayers (together) with one iqama.

وَحَدَّثَنِيهِ زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ وَقَالَ صَلاَّهُمَا بِإِقَامَةٍ وَاحِدَةٍ ‏.‏