This is a dua the angels love so much! 

A Companion RA of Rasulullah Said One day we were praying behind the Messenger of Allah ﷺ and when he ﷺ 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: رَبَّنَـا وَلَكَ الحَمْـدُ حَمْـدًا كَثِـيرًا طَيِّـبًا مُـبَارَكاً فِيه “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 ﷺ said: ‘Who spoke?’ The man said, ‘I did’. He ﷺ said, ‘Indeed I saw some 30 angels all scuffling to see which one of them could record it.’ [Muslim]