'Nights' in the Bible

When I went up the mountain to receive the stone tablets, the tablets of the covenant that the Lord made with you, I remained there forty days and nights, eating and drinking nothing.

Now at the end of the forty days and nights the Lord presented me with the two stone tablets, the tablets of the covenant.

Then I again fell down before the Lord for forty days and nights; I ate and drank nothing because of all the sin you had committed, doing such evil before the Lord as to enrage him.

I lay flat on the ground before the Lord for forty days and nights, for he had said he would destroy you.

As for me, I stayed at the mountain as I did the first time, forty days and nights. The Lord listened to me that time as well and decided not to destroy you.