(the mother of the faithful believers) I never saw Messenger of Allah ﷺ offering the night prayer while sitting except in his old age and then he used to recite while sitting and whenever he wanted to bow he would get up and recite thirty or forty verses (while standing) and then bow.  

عَنْ عَائِشَةَ ؓ أُمِّ الْمُؤْمِنِينَ أَنَّهَا أَخْبَرَتْهُ أَنَّهَا لَمْ تَرَ رَسُولَ اللَّهِ ﷺ يُصَلِّي صَلاَةَ اللَّيْلِ قَاعِدًا قَطُّ حَتَّى أَسَنَّ فَكَانَ يَقْرَأُ قَاعِدًا حَتَّى إِذَا أَرَادَ أَنْ يَرْكَعَ قَامَ فَقَرَأَ نَحْوًا مِنْ ثَلاَثِينَ آيَةً أَوْ أَرْبَعِينَ آيَةً ثُمَّ رَكَعَ  

(the mother of the faithful believers) Messenger of Allah ﷺ (in his last days) used to pray sitting. He would recite while sitting, and when thirty or forty verses remained from the recitation he would get up and recite them while standing and then he would bow and prostrate. He used to do the same in the second rakʿa. After finishing the Prayer he used to look at me and if I was awake he would talk to me and if I was asleep, he would lie down.  

عَنْ عَائِشَةَ أُمِّ الْمُؤْمِنِينَ ؓ أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُصَلِّي جَالِسًا فَيَقْرَأُ وَهْوَ جَالِسٌ فَإِذَا بَقِيَ مِنْ قِرَاءَتِهِ نَحْوٌ مِنْ ثَلاَثِينَ أَوْ أَرْبَعِينَ آيَةً قَامَ فَقَرَأَهَا وَهْوَ قَائِمٌ ثُمَّ يَرْكَعُ ثُمَّ يَسْجُدُ يَفْعَلُ فِي الرَّكْعَةِ الثَّانِيَةِ مِثْلَ ذَلِكَ فَإِذَا قَضَى صَلاَتَهُ نَظَرَ فَإِنْ كُنْتُ يَقْظَى تَحَدَّثَ مَعِي وَإِنْ كُنْتُ نَائِمَةً اضْطَجَعَ