Mu'adh bin Hisham said:"My father narrated to me, from Qatadah, from Zurarah bin Awfa, from Sa'd bin Hisham, that Aishah said: 'When the Messenger of Allah (ﷺ) prayed witr with nine rak'ahs, he did not sit until the eighth rak'ah. Then he would praise Allah (SWT) and remember Him and supplicate, then he would get up and he wouldn't say the taslim, then he prayed the ninth, then he sat and remembered Allah (SWT) and supplicated. Then he said a taslim that we could hear. Then he prayed two rak'ahs sitting down. When he grew older and weaker, he prayed witr with seven rak'ahs and did not sit until the sixth. Then he got up and did not say the taslim, and prayed the seventh, then he said the taslim, then he prayed two rak'ahs sitting down.'"
أَخْبَرَنَا زَكَرِيَّا بْنُ يَحْيَى، قَالَ حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا مُعَاذُ بْنُ هِشَامٍ، قَالَ حَدَّثَنِي أَبِي، عَنْ قَتَادَةَ، عَنْ زُرَارَةَ بْنِ أَوْفَى، عَنْ سَعْدِ بْنِ هِشَامٍ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا أَوْتَرَ بِتِسْعِ رَكَعَاتٍ لَمْ يَقْعُدْ إِلاَّ فِي الثَّامِنَةِ فَيَحْمَدُ اللَّهَ وَيَذْكُرُهُ وَيَدْعُو ثُمَّ يَنْهَضُ وَلاَ يُسَلِّمُ ثُمَّ يُصَلِّي التَّاسِعَةَ فَيَجْلِسُ فَيَذْكُرُ اللَّهَ عَزَّ وَجَلَّ وَيَدْعُو ثُمَّ يُسَلِّمُ تَسْلِيمَةً يُسْمِعُنَا ثُمَّ يُصَلِّي رَكْعَتَيْنِ وَهُوَ جَالِسٌ فَلَمَّا كَبِرَ وَضَعُفَ أَوْتَرَ بِسَبْعِ رَكَعَاتٍ لاَ يَقْعُدُ إِلاَّ فِي السَّادِسَةِ ثُمَّ يَنْهَضُ وَلاَ يُسَلِّمُ فَيُصَلِّي السَّابِعَةَ ثُمَّ يُسَلِّمُ تَسْلِيمَةً ثُمَّ يُصَلِّي رَكْعَتَيْنِ وَهُوَ جَالِسٌ .
Nesai
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day • Hadith 1719