Deuteronomy 9:18; Deuteronomy 9:25

18 Then I lay prostrate before the LORD as before, forty days and forty nights. I neither ate bread nor drank water, because of all the sin that you had committed, in doing what was evil in the sight of the LORD to provoke him to anger.

25 "So I lay prostrate before the LORD for these forty days and forty nights, because the LORD had said he would destroy you.