Messenger of Allah ﷺ said, "When the Imam, during the prayer, says, "Allah hears him who praises Him', say: 'O Allah! Our Lord! All the praises are for You/, for if the saying of anyone of you coincides with the saying of the angels, his past sins will be forgiven."

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا قَالَ الإِمَامُ سَمِعَ اللَّهُ لِمَنْ حَمِدَهُ فَقُولُوا اللَّهُمَّ رَبَّنَا لَكَ الْحَمْدُ فَإِنَّهُ مَنْ وَافَقَ قَوْلُهُ قَوْلَ الْمَلاَئِكَةِ غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ