'Head Covered' in the Bible

But David went up by the ascent of the Olives, and wept as he went up, and had his head covered, and he went barefoot; and all the people that was with him covered every man his head, and they went up, weeping as they went up.

And Mordecai came again to the king's gate. But Haman hasted to his house, mourning and having his head covered.

For man indeed ought not to have his head covered, being God's image and glory; but woman is man's glory.