Authentic Supplication Number 93.

Rifa’atu bin Rafi’ in said: One day we were praying behind the Prophet ┬áthen, when he lifted his head from the bow he said: Sami`al-lahu liman hamidahu (110) then, a man behind him said: Rabbana walakal-hamdu hamdan katheeran tayyiban mubarakan feehi (110)), then after the prayer he asked: “Who was the speaker?”. He said: I, He said: “I saw thirty plus Angels hastening to them (112), who would write them first”.

(110) Allah hears the one that praises Him.
(111) Our Lord and to You is All-Praise, praise that is plentiful, purely good, and blessed.
(112) Racing to write these words due to their greatness.

Reported by Muslim, and is #76 in The Authentic of Good Sayings.