Sahih Muslim 929
The Book of Prayers
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا حُمَيْدُ بْنُ عَبْدِ الرَّحْمَنِ الرُّؤَاسِيُّ، عَنْ أَبِيهِ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، قَالَ صَلَّى بِنَا رَسُولُ اللَّهِ صلى الله عليه وسلم وَأَبُو بَكْرٍ خَلْفَهُ فَإِذَا كَبَّرَ رَسُولُ اللَّهِ صلى الله عليه وسلم كَبَّرَ أَبُو بَكْرٍ لِيُسْمِعَنَا . ثُمَّ ذَكَرَ نَحْوَ حَدِيثِ اللَّيْثِ .
Jabir said:The Messenger of Allah (ﷺ) led the prayer and Abu Bakr was behind him. When the Messenger of Allah (ﷺ) recited the takbir, Abu Bakr also recited (it) in order to make it audible to us. And the rest of the hadith is like one transmitted by Laith
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.