Indeed I saw some 30 angels all scuffling to see which one of them could record it

One day we were praying behind the Messenger of Allah - sallallaahu ‘alayhi wa sallam - and when he  - sallallaahu ‘alayhi wa sallam -  raised his head from the position
of ruku` (bowing position), he said: “Sami Allahu leman hamidah” – ‘Allah hears the one who praises Him’. A man from behind added: 

رَبَّنـا وَلَكَ الحَمْـدُ حَمْـداً كَثـيراً طَيِّـباً مُـبارَكاً فيه

“Rabbanaa wa la kal hamd, hamdan katheeran tayyiban mubaarakan feeh”

‘Our Lord, all praise is due only to You, praise which is abundant, excellent and blessed.’

When we finished [the prayer] the Prophet  - sallallaahu ‘alayhi wa sallam -  said: ‘Who spoke?’ The man said, ‘I did’. He  - sallallaahu ‘alayhi wa sallam - said,

‘Indeed I saw some 30 angels all scuffling to see which one of them could record it.’

[Muslim]