Charles Spurgeon Commentary Galatians 3:18-19

"For if the inheritance is of the law, it is no more of promise: but God hath granted it to Abraham by promise. 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." — Galatians 3:18-19 (ASV)

But God gave it to Abraham by promise. Wherefore then serveth the law?

What was the use of that?