'Heels' in the Bible

Dan is a serpent by the way, An adder by the path, Which is biting the horse's heels, And its rider falleth backward.

They assemble, they hide, they watch my heels, When they have expected my soul.

And when thou dost say in thy heart, 'Wherefore have these met me?' For the abundance of thine iniquity Have thy skirts been uncovered, Have thy heels suffered violence.