It wasnarrated that 'Aishah said:
"The Messenger of Allah (ﷺ) fellill and some of his Companions came to visit him. The Messenger ofAllah (ﷺ) performed prayer while sitting down, and they prayedbehind him standing up. He gestured them to sit down, and when hefinished he said: 'The Imam is appointed to be followed. When hebows,then bow; when he stands up again, then stand up, and if heprayssitting down then pray sitting down.'"
English reference: Vol. 1, Book 5, Hadith 1237
Arabic reference: Book 5, Hadith 1295