The Messenger of Allah ﷺ prayed during his illness while seated, and a group of people behind him prayed standing. He gestured to them to sit down. When he finished his prayer, he said, "The imam is appointed only to be followed. When he bows, bow. When he rises, rise. And when he prays seated, pray seated."
حدثنا ابن نمير عن هشام عن أبيه
أن رسول الله ﷺ صلى في مرضه وهو جالس فصلى وخلفه قوم قياما فأشار إليهم أن اجلسوا فلما قضى صلاته قال إنما الإمام ليؤتم به فإذا ركع فاركعوا وإذا رفع فارفعوا وإذا صلى جالسا فصلوا جلوسا