Sunan Ibn Majah, Chapter: The Chapters on Etiquette

the Messenger of Allah (saw) told them: "One of the slaves of Allah said: 'Ya Rabb! Lakal-hamdu kama yanbagi li-jalali Wajhika wa li 'azima sultanika (O Lord, to You is praise as befits the Glory of Your Face and the greatness of Your Might.)' The angels were uncertain and did not know how to write this down, so they ascended to heaven and said: 'O our Lord, Your slave has said a word that we do not know how to write down.' Allah said - and He knows best what His slave said - 'What did My slave say?' They said: 'O Lord, he said "Ya Rabb! Lakal-hamdu kama yanbagi li-jalali Wajhika wa li'azima sultanika (O Lord, to You is praise as befits the Glory of Your Face and the greatness of your Might).'" Allah said to them: 'Write it down as My slave said it, until he meets Me and I shall reward him for it.'"