'Played the Fool' in the Bible

Then said Saul, I have sinned: return, my son David: for I will no more do thee harm, because my soul was precious in thine eyes this day: behold, I have played the fool, and have erred exceedingly.

Then I thought:They are just the poor;they have played the fool.For they don’t understand the way of the Lord,the justice of their God.