An Nasai: Hadith 3895

"I noticed that the Messenger of Allah was not there one night, and I thought that he had gone to one of his other wives. I looked for him then I came back, and there he was, bowing or prostrating and saying: 'Subhanaka wa bi hamdika la ilaha illa anta (Glory and praise be to You, there is none worthy of worship but You).' I said: 'May my father and mother be sacrificed for you; you were doing one thing and I was thinking of something else.'"