حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ الْمِصْرِيُّ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، قَالَ اشْتَكَى رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ فَصَلَّيْنَا وَرَاءَهُ وَهُوَ قَاعِدٌ وَأَبُو بَكْرٍ يُكَبِّرُ يُسْمِعُ النَّاسَ تَكْبِيرَهُ فَالْتَفَتَ إِلَيْنَا فَرَآنَا قِيَامًا فَأَشَارَ إِلَيْنَا فَقَعَدْنَا فَصَلَّيْنَا بِصَلاَتِهِ قُعُودًا فَلَمَّا سَلَّمَ قَالَ ‏"‏ إِنْ كِدْتُمْ أَنْ تَفْعَلُوا فِعْلَ فَارِسَ وَالرُّومِ يَقُومُونَ عَلَى مُلُوكِهِمْ وَهُمْ قُعُودٌ فَلاَ تَفْعَلُوا ائْتَمُّوا بِأَئِمَّتِكُمْ إِنْ صَلَّى قَائِمًا فَصَلُّوا قِيَامًا وَإِنْ صَلَّى قَاعِدًا فَصَلُّوا قُعُودًا ‏"‏ ‏.‏

It wasnarrated that Jabir said: “The Messenger of Allah (PBUH) fellill,and we prayed behind him while he was sitting down, and Abu Bakrwassaying the Takbir so that the people could hear them. He turned tousand saw us standing, so he gestured to us to sit down. When he hadsaid the Salam, he said: ‘You were about to do the action of thePersians and Romans, who remain standing while their kings areseated.Do not do that. Follow the lead of your Imam; if he praysstanding,then pray standing, and if he prays sitting down, then praysittingdown.’” Translation Not Available

Book Ref: Sunan Ibn Majah Book 5 Hadith 1240
Web Ref:  Sunan Ibn Majah Vol 1 Book 5 Hadith 1240