It was narrated from Salim, from his father, that the Prophet ﷺ joined them (Maghrib and 'Isha') in Al-Muzdalifah, and he prayed each of them with an Iqamah, and he did not offer any voluntary prayer before or after either of them. (Using translation from Nasāʾī 660)
أَنَّ النَّبِيَّ ﷺ جَمَعَ بَيْنَهُمَا بِالْمُزْدَلِفَةِ وَصَلَّى كُلَّ وَاحِدَةٍ مِنْهُمَا بِإِقَامَةٍ وَلَمْ يَتَطَوَّعْ قَبْلَ كُلِّ وَاحِدَةٍ مِنْهُمَا وَلَا بَعْدَهَا