Never did I see the Messenger of Allah ﷺ observing supererogatory prayer sitting till one year before his death when he would observe Nafl prayer in a sitting position, and he would recite the Surah (of the Qur'an) in such a slow-measured tone (that duration of its recital) became more lengthy than the one longer than this.  

أَنَّهَا قَالَتْ مَا رَأَيْتُ رَسُولَ اللَّهِ ﷺ صَلَّى فِي سُبْحَتِهِ قَاعِدًا حَتَّى كَانَ قَبْلَ وَفَاتِهِ بِعَامٍ فَكَانَ يُصَلِّي فِي سُبْحَتِهِ قَاعِدًا وَكَانَ يَقْرَأُ بِالسُّورَةِ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا  

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  

that she said, "I never saw the Messenger of Allāh ﷺ pray his supererogatory prayers while sitting; until a year before his passing when he would his supererogatory prayers while sitting and reciting the sūrah in ˹such a slow˺ measured manner that it became longer than his ˹usual˺ longer ones."  

أَنَّهَا قَالَتْ لَمْ أَرَ رَسُولَ اللهِ ﷺ يُصَلِّي فِي سُبْحَتِهِ جَالِسًا قَطُّ حَتَّى إِذَا كَانَ قَبْلَ مَوْتِهِ بِعَامٍ أَوْ بِعَامَيْنِ فَكَانَ يُصَلِّي فِي سُبْحَتِهِ جَالِسًا وَيَقْرَأُ السُّورَةَ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا  

that she said, "I never saw the Messenger of Allāh ﷺ pray his supererogatory prayers while sitting; until a year before his passing when he would his supererogatory prayers while sitting and reciting the sūrah in ˹such a slow˺ measured manner that it became longer than his ˹usual˺ longer ones." (Using translation from Aḥmad 26441)   

مَا رَأَيْتُ رَسُولَ اللهِ ﷺ يُصَلِّي فِي سُبْحَتِهِ جَالِسًا قَطُّ حَتَّى كَانَ قَبْلَ مَوْتِهِ بِعَامٍ فَكَانَ يُصَلِّي جَالِسًا فَيَقْرَأُ السُّورَةَ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا  

[Machine] "Hafsah, the wife of the Prophet ﷺ , said, 'I have never seen the Messenger of Allah ﷺ praying while sitting until close to the time of his passing, which was about a year or two before his death. I saw him praying while sitting, reciting the Surah until it became longer than any other Surah.'"  

أَنَّ حَفْصَةَ زَوْجَ النَّبِيِّ ﷺ قَالَتْ «لَمْ أَرَ رَسُولَ اللَّهِ ﷺ يُصَلِّي فِي سُبْحَتِهِ وَهُوَ جَالِسٌ حَتَّى كَانَ قَبْلَ أَنْ يُتَوَفَّى بِعَامٍ وَاحِدٍ أَوْ عَامَيْنِ فَرَأَيْتُهُ يُصَلِّي فِي سُبْحَتِهِ وَهُوَ جَالِسٌ فَيُرَتِّلُ السُّورَةَ حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا»  

that she said, "I never saw the Messenger of Allāh ﷺ pray his supererogatory prayers while sitting; until a year before his passing when he would his supererogatory prayers while sitting and reciting the sūrah in ˹such a slow˺ measured manner that it became longer than his ˹usual˺ longer ones." (Using translation from Aḥmad 26441)   

«مَا رَأَيْتُ النَّبِيَّ ﷺ صَلَّى فِي سُبْحَتِهِ جَالِسًا قَطُّ حَتَّى كَانَ قَبْلَ وَفَاتِهِ بِعَامٍ فَكَانَ يُصَلِّي فِي سُبْحَتِهِ جَالِسًا فَيَقْرَأُ السُّورَةَ فَيُرَتِّلُهَا حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا»  

[Machine] Hafsah, the wife of the Prophet ﷺ, said, "I never saw the Messenger of Allah ﷺ praying while sitting until a year before his death. Then I saw him praying while sitting and reciting the Surah until its length became greater than the length he used to recite."  

أَنَّ حَفْصَةَ زَوْجَ النَّبِيِّ ﷺ قَالَتْ «لَمْ أَرَ رَسُولَ اللَّهِ ﷺ يُصَلِّي فِي سُبْحَتِهِ وَهُوَ جَالِسٌ حَتَّى كَانَ ﷺ قَبْلَ مَوْتِهِ بِعَامٍ وَاحِدٍ فَرَأَيْتُهُ يُصَلِّي فِي سُبْحَتِهِ وَهُوَ جَالِسٌ وَيُرَتِّلُ السُّورَةَ حَتَّى تَكُونَ أَطْوَلَ مِنْ أَطْوَلَ مِنْهَا»  

"لَمْ أَرَ رَسُولَ اللهِ ﷺ يُصَلِّي قَاعِدًا حَتَّى كَانَ قَبْلَ مَوْتِهِ بِعَامٍ أَوِ اثْنَيْنِ، وَكَانَ يُصَلِّي فِي سُبْحَتِهِ جَالِسًا، وَيرَتِّلُ السُّورَةَ حَتَّى تَكُونَ فِي قرَاءَتِهِ أَطْوَلَ مِنْ أَطْوَل مِنْهَا".