Deuteronomy 9:18, 25

And I fell down before the LORD, as at the first, forty days and forty nights: I did neither eat bread, nor drink water, because of all your sins which ye sinned, in doing wickedly in the sight of the LORD, to provoke him to anger.

Thus I fell down before the LORD forty days and forty nights, as I fell down at the first; because the LORD had said he would destroy you.