The Prophet ﷺ offered the Maghrib and ʿIsha' prayers together at Jam' (i.e. Al-Muzdalifa) with a separate Iqama for each of them and did not offer any optional prayer in between them or after each of them.  

جَمَعَ النَّبِيُّ ﷺ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ كُلُّ وَاحِدَةٍ مِنْهُمَا بِإِقَامَةٍ وَلَمْ يُسَبِّحْ بَيْنَهُمَا وَلاَ عَلَى إِثْرِ كُلِّ وَاحِدَةٍ مِنْهُمَا  

the Messenger of Allah joined Maghrib and Isha; in Jam (Al-Muzdalifah), with one Iqamah, and he did not offer any voluntary prayers in between or after either of them. (Using translation from Nasāʾī 3028)  

أَنَّ رَسُولَ اللهِ ﷺ جَمَعَ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ بِإِقَامَةٍ وَلَمْ يُسَبِّحْ بَيْنَهُمَا وَلَا عَلَى أَثَرِ وَاحِدَةٍ مِنْهُمَا  

Ibn 'Umar rep rte that Messenger of Allah ﷺ combined the sunset and 'Isha ' prayers at Muzdalifa. He observed three rak'ahs of the sunset prayer and two rak'ahs of the 'Isha' prayer with one Iqama. (Using translation from Muslim 1288d)  

أَنَّ النَّبِيَّ ﷺ جَمَعَ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ صَلَّى الْمَغْرِبَ ثَلَاثًا وَالْعِشَاءَ رَكْعَتَيْنِ بِإِقَامَةٍ وَاحِدَةٍ  

[Machine] "That the Prophet of Allah, peace be upon him, performed the Maghrib and Isha prayers in Muzdalifah without calling the adhan in either of them, except with the Iqamah. He did not offer any additional supplications (tasbih) between the prayers or after one of them."  

«أَنَّ النَّبِيَّ اللَّهُ ﷺ صَلَّى الْمَغْرِبَ وَالْعِشَاءَ بِالْمُزْدَلِفَةِ لَمْ يُنَادِ فِي وَاحِدَةٍ مِنْهُمَا إِلَّا بِالْإِقَامَةِ وَلَمْ يُسَبِّحْ بَيْنَهُمَا وَلَا عَلَى إِثْرِ وَاحِدَةٍ مِنْهُمَا»  

the Messenger of Allah joined Maghrib and Isha; in Jam (Al-Muzdalifah), with one Iqamah, and he did not offer any voluntary prayers in between or after either of them. (Using translation from Nasāʾī 3028)  

أَنَّ رَسُولَ اللهِ ﷺ «جَمَعَ بَيْنَ الْمَغْرِبِ وَالْعِشَاءِ بِجَمْعٍ بِإِقَامَةٍ وَاحِدَةٍ لَمْ يُسَبِّحْ بَيْنَهُمَا وَلَا عَلَى إِثْرِ وَاحِدَةٍ مِنْهُمَا»