(16) باب جَوَازِ النَّافِلَةِ قَائِمًا وَقَاعِدًا وَفِعْلِ بَعْضِ الرَّكْعَةِ قَائِمًا وَبَعْضِهَا قَاعِدًا
Jabir b. Samura reported that the Messenger of Allah (ﷺ) observed (Nafl) prayer sitting before his death.
Reference: Sahih Muslim 734
In-book reference: Book 6, Hadith 144
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1599