The Messenger of Allah ﷺ offered the night prayer and then prayed eight rak'ahs standing, and two rak'ahs between the two adhans (i.e. the adhan for the dawn prayer and the iqamah). He never left them. Jaf'ar b. Musafir said in his version: (He prayed) the two rak'ahs sitting between the two adhans. He added the word "sitting".
أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى الْعِشَاءَ ثُمَّ صَلَّى ثَمَانِيَ رَكَعَاتٍ قَائِمًا وَرَكْعَتَيْنِ بَيْنَ الأَذَانَيْنِ وَلَمْ يَكُنْ يَدَعُهُمَا قَالَ جَعْفَرُ بْنُ مُسَافِرٍ فِي حَدِيثِهِ وَرَكْعَتَيْنِ جَالِسًا بَيْنَ الأَذَانَيْنِ زَادَ جَالِسًا