“The Messenger of Allah (ﷺ) fell
ill,
and we prayed behind him while he was sitting down, and Abu Bakr
was
saying the Takbir so that the people could hear them. He turned to
us
and saw us standing, so he gestured to us to sit down. When he had
said the Salam, he said: ‘You were about to do the action of the
Persians and Romans, who remain standing while their kings are
seated.
Do not do that. Follow the lead of your Imam; if he prays
standing,
then pray standing, and if he prays sitting down, then pray
sitting
down.’”
Sunan Ibn Majah Book 5, Hadith 438