Musnad Ahmad Hadith 14590

It is narrated from Jabir (may Allah be pleased with him) that once the Prophet (ﷺ) became ill. We performed prayer behind the Prophet (ﷺ) at that time, and he was leading the prayer while sitting. Siddiq Akbar (Abu Bakr) was loudly saying the takbeer so that others could hear the takbeer. The Prophet (ﷺ) glanced at us from the corner of his eye and saw that we were standing. The Prophet (ﷺ) gestured towards us, so we also began to pray sitting, and completed the rest of the prayer in this manner. After finishing the prayer, the Prophet (ﷺ) said: "It was just about that you would have started doing as the people of Persia and Rome do. They also stand before their kings while the kings remain seated. Do not do so; rather, follow your imams. If they pray standing, then you should also pray standing. If they pray sitting, then you should also pray sitting."