Messenger of Allah ﷺ offered the ʿIsha' prayer (and then got up at the Tahajjud time) and offered eight rakʿat and then offered two rakʿat while sitting. He then offered two rakʿat in between the Adhan and Iqama (of the Fajr prayer) and he never missed them.  

صَلَّى النَّبِيُّ ﷺ الْعِشَاءَ ثُمَّ صَلَّى ثَمَانَ رَكَعَاتٍ وَرَكْعَتَيْنِ جَالِسًا وَرَكْعَتَيْنِ بَيْنَ النِّدَاءَيْنِ وَلَمْ يَكُنْ يَدَعُهُمَا أَبَدًا  

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  

[Machine] The Messenger of Allah, ﷺ , performed the night prayer, then he prayed eight units of prayer while standing and two units of prayer while sitting between the call to prayer, and he would never abandon them.  

صَلَّى رَسُولُ اللهِ ﷺ الْعِشَاءَ ثُمَّ صَلَّى ثَمَانِ رَكَعَاتٍ قَائِمًا وَرَكْعَتَيْنِ جَالِسًا بَيْنَ النِّدَاءَيْنِ لَمْ يَكُنْ يَدَعُهُمَا  

Messenger of Allah ﷺ offered the ʿIsha' prayer (and then got up at the Tahajjud time) and offered eight rakʿat and then offered two rakʿat while sitting. He then offered two rakʿat in between the Adhan and Iqama (of the Fajr prayer) and he never missed them. (Using translation from Bukhārī 1159)   

«صَلَّى رَسُولُ اللهِ ﷺ الْعِشَاءَ ثُمَّ صَلَّى ثَمَانِيَ رَكَعَاتٍ قَائِمًا وَرَكْعَتَيْنِ جَالِسًا وَرَكْعَتَيْنِ بَيْنَ النِّدَاءَيْنِ وَلَمْ يَكُنْ يَدَعُهُمَا»