سنن النسائي

It was narrated that 'Aishah said: "I noticed that the Messenger of Allah (ﷺ) was missing one night, and I thought he had gone to one of his other wives. I tried to feel for him, and I found him bowing or prostrating and saying: 'SubhanakAllahumma wa bihamdika la ilaha ila ant (Glory and praise be to You, O Allah, there is none worthy of worship but You.)'" She said: "May my father and mother be ransomed for you. I thought you were doing one thing and you were doing something else altogether."