Charles Spurgeon Commentary Galatians 3:19-21

"What then is the law? It was added because of transgressions, till the seed should come to whom the promise hath been made; [and it was] ordained through angels by the hand of a mediator. Now a mediator is not [a mediator] of one; but God is one. Is the law then against the promises of God? God forbid: for if there had been a law given which could make alive, verily righteousness would have been of the law." — Galatians 3:19-21 (ASV)

And it was ordained by angels in the hand of a mediator.

Now a mediator is not a mediator of one, but God is one. Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law.

There could not have been a better law. Some talk about the law of God being too severe, too strict, too stringent, but it is not. If the design had been that men should live by the law, there could not have been a better law for that purpose; and hence it is proved that, by the principle of law nobody ever can be justified because, even with the best of laws, all men are sinful, and so need that justification which comes only by grace through faith.