'A'isha reported that the Messenger of Allah ﷺ died (in this very state) that he observed most of his (Nafl) prayers in a sitting position. (Using translation from Muslim 732c)
أَنَّ رَسُولَ اللهِ ﷺ لَمْ يَمُتْ حَتَّى كَانَ «كَثِيرٌ مِنْ صَلَاتِهِ وَهُوَ جَالِسٌ»