It was narrated from Sa'eed bin Jubair that he prayed Maghrib and 'Isha' in Jam' (Muzdalifah) with one Iqamah, then he narrated that Ibn 'Umar had done that, and Ibn 'Umar narrated that the Prophet ﷺ had done that.  

أَنَّهُ صَلَّى الْمَغْرِبَ وَالْعِشَاءَ بِجَمْعٍ بِإِقَامَةٍ وَاحِدَةٍ ثُمَّ حَدَّثَ عَنِ ابْنِ عُمَرَ أَنَّهُ صَنَعَ مِثْلَ ذَلِكَ وَحَدَّثَ ابْنُ عُمَرَ أَنَّ النَّبِيَّ ﷺ صَنَعَ مِثْلَ ذَلِكَ