Jabir b. Samura reported that the Messenger of Allah (ﷺ) observed (Nafl) prayer sitting before his death.
Sahih Muslim Book 6, Hadith 144
← Previous Hadith Zuhri reported this hadith with the same chain of transmitters, except this that he made a mention of one year or two years.

Sahih Muslim Book 6, Hadith 143 Next Hadith → It was narrated to me that the Messenger of Allah (ﷺ) had said: The prayer observed by a person sitting is half of the prayer. I came to him (ﷺ) and found him praying in a sitting position. I placed my hand on his head. He said: O 'Abdullah b. 'Amr, what is the matter with you? I said: Messenger of Allah, it has been narrated to me that you said: The prayer of a man in a sitting position is half of the prayer, whereas you are observing prayer sitting. He (the Holy Prophet) said: Yes, it is so, but I am not like anyone amongst you.

Sahih Muslim Book 6, Hadith 145