The Prophet ﷺ said: Do not try to outstrip me in bowing and prostrating because however earlier I bow you will join me when I raise (my head from bowing); I have become bulky.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ تُبَادِرُونِي بِرُكُوعٍ وَلاَ بِسُجُودٍ فَإِنَّهُ مَهْمَا أَسْبِقْكُمْ بِهِ إِذَا رَكَعْتُ تُدْرِكُونِي بِهِ إِذَا رَفَعْتُ إِنِّي قَدْ بَدَّنْتُ  

Al-Bara who is not a liar said; when they (the companions) raised their heads from bowing along with the Messenger of Allah ﷺ, they would stand up, and when they saw him that he went down in prostration, they would prostrate (following the prophet).  

حَدَّثَنَا الْبَرَاءُ وَهُوَ غَيْرُ كَذُوبٍ أَنَّهُمْ كَانُوا إِذَا رَفَعُوا رُءُوسَهُمْ مِنَ الرُّكُوعِ مَعَ رَسُولِ اللَّهِ ﷺ قَامُوا قِيَامًا فَإِذَا رَأَوْهُ قَدْ سَجَدَ سَجَدُوا  

Al-Bara b.‘Azib said ; we used to pray along with the prophet ﷺ; none of us bowed his back until he saw that the prophet ﷺ bowed (his back).  

كُنَّا نُصَلِّي مَعَ النَّبِيِّ ﷺ فَلاَ يَحْنُو أَحَدٌ مِنَّا ظَهْرَهُ حَتَّى يَرَى النَّبِيَّ ﷺ يَضَعُ  

then they would follow him ﷺ  

حَدَّثَنِي الْبَرَاءُ أَنَّهُمْ كَانُوا يُصَلُّونَ مَعَ رَسُولِ اللَّهِ ﷺ فَإِذَا رَكَعَ رَكَعُوا وَإِذَا قَالَ سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ لَمْ نَزَلْ قِيَامًا حَتَّى يَرَوْهُ قَدْ وَضَعَ جَبْهَتَهُ بِالأَرْضِ ثُمَّ يَتَّبِعُونَهُ ﷺ