Why the law then? It was added because of transgressions until the Seed to whom the promise was made would come. [The law] was ordered through angels by means of a mediator.
References for Galatians 3:19
Now a mediator is not for just one person, but God is one.
Is the law therefore contrary to God's promises? Absolutely not! For if a law had been given that was able to give life, then righteousness would certainly be by the law.
But the Scripture has imprisoned everything under sin's power, so that the promise by faith in Jesus Christ might be given to those who believe.
References for Galatians 3:22
Before this faith came, we were confined under the law, imprisoned until the coming faith was revealed.
The law, then, was our guardian described such a slave. This slave was not a teacher. until Christ, so that we could be justified by faith.
References for Galatians 3:24
But since that faith has come, we are no longer under a guardian, described such a slave. This slave was not a teacher.
References for Galatians 3:25