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