'Days' in the Bible

Now the Lord had prepared (appointed, destined) a great fish to swallow Jonah. And Jonah was in the stomach of the fish three days and three nights.

So Jonah went to Nineveh in accordance with the word of the Lord. Now Nineveh was an exceedingly great city, a three days’ walk [about sixty miles in circumference].

Then on the first day’s walk, Jonah began to go through the city, and he called out and said, “Forty days more [remain] and [then] Nineveh will be overthrown!”