Rabbana wa lakal-hamd

Saying "Our Lord, to You is praise" with the angels brings forgiveness.

Narrated by Abu Hurairah

When the imam says "Sami'a Allahu liman hamidah" (Allah hears whoever praises Him), say: "Allahumma Rabbana lakal-hamd" (O Allah, our Lord, to You is all praise). Whoever's words coincide with the words of the angels, his past sins will be forgiven.

Sahih al-Bukhari 796, Sahih Muslim 409

What this hadith teaches

A short phrase said on rising from bowing, with the reward of complete forgiveness.

Reference and grade

Grade
Sahih: agreed upon by al-Bukhari and Muslim
Narrator
Abu Hurairah

The hadith in Arabic نص الحديث

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

Arabic text of Sahih al-Bukhari 796, as given on sunnah.com.