I said to 'A'isha and she made a mention of that (recorded above) about the Messenger of Allah (ﷺ).
Sahih Muslim Book 6, Hadith 139
← Previous Hadith I asked 'A'isha whether the Messenger of Allah (ﷺ) observed (Nafl) sitting. She said: Yes, when the people had made him old.

Sahih Muslim Book 6, Hadith 138 Next Hadith → '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.

Sahih Muslim Book 6, Hadith 140