Sunan an-Nasa'i 1200

Qutaybah reported to us; he said: al-Layth reported to us, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (ﷺ) fell ill, and we prayed behind him while he was seated. Abu Bakr was saying the takbir so that the people could hear his takbir. He turned toward us, saw that we were standing, and gestured to us, so we sat down and prayed following his prayer while seated. When he said the taslim, he said: “A short while ago you were doing what the Persians and Romans do: they stand before their kings while those kings are seated. Do not do that. Follow your imams: if he prays standing, then pray standing; and if he prays seated, then pray seated.”