Deuteronomy 9:18
"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."
Cross References (ranked by relevance)
And he was there with the LORD forty days and forty nights; he did neither eat bread, nor drink water. And he wrote upon the tables the words of the covenant, the ten commandments.
When I was gone up into the mount to receive the tables of stone, even the tables of the covenant which the LORD made with you, then I abode in the mount forty days and forty nights, I neither did eat bread nor drink water:
Therefore he said that he would destroy them, had not Moses his chosen stood before him in the breach, to turn away his wrath, lest he should destroy them.
And I stayed in the mount, according to the first time, forty days and forty nights; and the LORD hearkened unto me at that time also, and the LORD would not destroy thee.
David therefore besought God for the child; and David fasted, and went in, and lay all night upon the earth.