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 رَسُولَ اللهِ ﷺ «جَمَعَ بَيْنَهُمَا بِالْمُزْدَلِفَةِ صَلَّى كُلَّ وَاحِدَةٍ مِنْهُمَا بِإِقَامَةٍ وَلَمْ يَتَطَوَّعْ قَبْلَ وَاحِدَةٍ مِنْهُمَا وَلَا بَعْدَهَا»