Hadithcore
Mishkat al-Masabih, 1136

Al-Bara’ b. ‘Azib said:

We used to pray behind the Prophet, and when he said, "God listens to him who praises Him," none of us bowed his back till the Prophet (ﷺ) placed his forehead on the ground. (Bukhari and Muslim.)

عَنِ الْبَرَاءِ بْنِ عَازِبٍ قَالَ: كُنَّا نُصَلِّي خَلْفَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَإِذَا قَالَ: «سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ» . لَمْ يَحْنِ أَحَدٌ مِنَّا ظَهْرَهُ حَتَّى يَضَعَ النَّبِيُّ صَلَّى الله عَلَيْهِ وَسلم جَبهته على الأَرْض

References1 variant
In-Book Reference
Book 4, Hadith 553