Yahya related to me from Malik from Ibn Shihab from as-Sa'ib ibn Yazid from al Muttalib ibn Abi Wadaa as-Sahmi that Hafsa, the wife of the Prophet ﷺ said, "I never saw the Messenger of Allah ﷺ praying nawafil sitting, until a year before his death, when he began to pray them sitting. He would recite the sura with a measured slowness so that it would seem to be longer than other suras which were actually longer than it."  

عَنْ حَفْصَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّهَا قَالَتْ مَا رَأَيْتُ رَسُولَ اللَّهِ ﷺ صَلَّى فِي سُبْحَتِهِ قَاعِدًا قَطُّ حَتَّى كَانَ قَبْلَ وَفَاتِهِ بِعَامٍ فَكَانَ يُصَلِّي فِي سُبْحَتِهِ قَاعِدًا وَيَقْرَأُ بِالسُّورَةِ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا  

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, the wife of the Prophet ﷺ told him that she had never seen the Messenger of Allah ﷺ doing night prayers sitting down until he was getting on in years. He would recite sitting down until when he wanted to go into ruku, he would stand up and recite about thirty or forty ayats and then go into ruku.  

عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ 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 أَوْ أَرْبَعِينَ آيَةً ثُمَّ رَكَعَ  

Yahya related to me from Malik from Abdullah ibn Yazid al-Madani and from Abu'n Nadr from Abu Salama ibn Abd ar-Rahman from A'isha, the wife of the Prophet ﷺ that the Messenger of Allah ﷺ used to pray sitting. He would recite sitting, and then, when about thirty or forty ayats of what he was reciting remained, he would stand up and recite standing and then go into ruku and sajda. He would do the same in the second raka.  

عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُصَلِّي جَالِسًا فَيَقْرَأُ وَهُوَ جَالِسٌ فَإِذَا بَقِيَ مِنْ قِرَاءَتِهِ قَدْرُ مَا يَكُونُ ثَلاَثِينَ أَوْ أَرْبَعِينَ آيَةً قَامَ فَقَرَأَ وَهُوَ قَائِمٌ ثُمَّ رَكَعَ وَسَجَدَ ثُمَّ صَنَعَ فِي الرَّكْعَةِ الثَّانِيَةِ مِثْلَ ذَلِكَ  

Yahya related to me from Malik that he had heard that Urwa ibn az-Zubayr and Said ibn al-Musayyab used to pray voluntary prayers sitting.  

أَنَّ عُرْوَةَ بْنَ الزُّبَيْرِ وَسَعِيدَ بْنَ الْمُسَيَّبِ كَانَا يُصَلِّيَانِ النَّافِلَةَ وَهُمَا مُحْتَبِيَانِ