Al-Adab Al-Mufrad, Book 40, Hadith 948 (English) ⓘ

Jabir said, "The Prophet, may Allah bless him and grant him peace, was ill and we prayed behind him while he was sitting down. Abu Bakr relayed his takbir to the people. The Prophet turned towards us and saw that we were standing. He indicated to us that we should sit down. So we prayed sitting down with him. When he said the taslim, he said, 'You were about to do what the Persians and Romans do. They stand in front of their kings when they are seated. Do not do that. Follow your Imams. If the Imam prays standing, then pray standing. If he prays sitting down, then pray sitting down."

حَدَّثَنَا عَبْدُ اللهِ بْنُ صَالِحٍ قَالَ‏:‏ حَدَّثَنِي اللَّيْثُ قَالَ‏:‏ حَدَّثَنِي أَبُو الزُّبَيْرِ، عَنْ جَابِرٍ قَالَ‏:‏ اشْتَكَى النَّبِيُّ صلى الله عليه وسلم، فَصَلَّيْنَا وَرَاءَهُ وَهُوَ قَاعِدٌ، وَأَبُو بَكْرٍ يُسْمِعُ النَّاسَ تَكْبِيرَهُ، فَالْتَفَتَ إِلَيْنَا فَرَآنَا قِيَامًا، فَأَشَارَ إِلَيْنَا فَقَعَدْنَا، فَصَلَّيْنَا بِصَلاَتِهِ قُعُودًا، فَلَمَّا سَلَّمَ قَالَ‏:‏ إِنْ كِدْتُمْ لَتَفْعَلُوا فِعْلَ فَارِسَ وَالرُّومِ، يَقُومُونَ عَلَى مُلُوكِهِمْ وَهُمْ قُعُودٌ، فَلاَ تَفْعَلُوا، ائْتَمُّوا بِأَئِمَّتِكُمْ، إِنْ صَلَّى قَائِمًا فَصَلُّوا قِيَامًا، وَإِنْ صَلَّى قَاعِدًا فَصَلُّوا قُعُودًا‏.‏