Sahih al-Bukhari 760

It is related that Rifa'a ibn Rafi' az-Zuraqi said, "One day, when we were praying behind the Prophet, may Allah bless him and grant him peace, as he raised his head from the ruku' he said, 'Allah hears whoever praises Him.' A man behind him said, 'Our Lord, praise belongs to You, abundant, good and blessed praise.' When he finished, he said, 'Who spoke?' The man said, 'I did.' The Prophet said, 'I saw about thirty angels racing each other to be first to write it down.' " LXIII: Coming to rest after raising the head from ruku' Abu Humayd said, "When the Prophet, may Allah bless him and grant him peace, raised his head, he stood upright until every vertebra had returned to its place."