The Book of Prayers
Ṣaḥīḥ Muslim 934
اللَّهُمَّ رَبَّنَا لَكَ الْحَمْدُ . فَإِذَا وَافَقَ قَوْلُ أَهْلِ الأَرْضِ قَوْلَ أَهْلِ السَّمَاءِ غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
Allāhumma rabbanā laka al-ḥamdu . fa-idhā wāfaqa qawlu ahli al-arḍi qawla ahli as-samāʾi ghufira lah mā taqaddama min dhanbihi
Transliteration generated from the Arabic vowel marks
The full narration
Abu Huraira reported:The Messenger of Allah (ﷺ) said: Verily the Imam is a shield, say prayer sitting when he says prayer sitting. And when he says:" Allah listens to him who praises Him," say:" O Allah, our Lord, to Thee be the praise." and when the utterance of the people of the earth synchronises with that of the beings of heaven (angels), all the previous sins would be pardoned
Source
Ṣaḥīḥ Muslim · 934
Ṣaḥīḥ
- Agreed upon as authentic (al-Bukhārī / Muslim)