'Three Days' in the Bible

Then the king said to Amasa, “Call out the men of Judah for me within three days, and be present here yourself.”

So Gad came to David and told him, and said to him, “Shall seven years of famine come to you in your land? Or will you flee three months before your foes while they pursue you? Or shall there be three days’ pestilence in your land? Now consider and see what answer I shall return to Him who sent me.”