"I never saw the Messenger of Allah ﷺ pray sitting down until he grew old. Then he would pray sitting down and when there were thirty or forty verses left, he would stand up and recite them, then bow."
مَا رَأَيْتُ رَسُولَ اللَّهِ ﷺ صَلَّى جَالِسًا حَتَّى دَخَلَ فِي السِّنِّ فَكَانَ يُصَلِّي وَهُوَ جَالِسٌ يَقْرَأُ فَإِذَا غَبَرَ مِنَ السُّورَةِ ثَلاَثُونَ أَوْ أَرْبَعُونَ آيَةً قَامَ فَقَرَأَ بِهَا ثُمَّ رَكَعَ