'Three Days' in the Bible

As for your asses which have been wandering for three days, give no thought to them, for they have come back. And for whom are all the desired things in Israel? are they not for you and your father's family?

And they gave him part of a cake of figs and some dry grapes; and after the food, his spirit came back to him, for he had had no food or drink for three days and nights.

And David said to him, Whose man are you and where do you come from? And he said, I am a young man of Egypt, servant to an Amalekite; and my master went on without me because three days back I became ill.