Galatians 3:17-19, 23-25

This is what I mean: the Law, which came into existence four hundred and thirty years later [after the covenant concerning the coming Messiah], does not and cannot invalidate the covenant previously established by God, so as to abolish the promise. [Ex 12:40] For if the inheritance [of what was promised] is based on [observing] the Law [as these false teachers claim], it is no longer based on a promise; however, God granted it to Abraham [as a gift] by virtue of His promise. Why, then, the Law [what was its purpose]? It was added [after the promise to Abraham, to reveal to people their guilt] because of transgressions [that is, to make people conscious of the sinfulness of sin], and [the Law] was ordained through angels and delivered to Israel by the hand of a mediator [Moses, the mediator between God and Israel, to be in effect] until the Seed would come to whom the promise had been made.

Now before faith came, we were kept in custody under the Law, [perpetually] imprisoned [in preparation] for the faith that was destined to be revealed, with the result that the Law has become our tutor and our disciplinarian to guide us to Christ, so that we may be justified [that is, declared free of the guilt of sin and its penalty, and placed in right standing with God] by faith. But now that faith has come, we are no longer under [the control and authority of] a tutor and disciplinarian.