This law that you speak of is not of morality, but of obedience. We do not follow what is right and wrong out of law, but out of love for God because He first loved us. The distinction here is that this obedience was directed at the Israelites. When Jesus fulfilled the law, we no longer are required or asked to follow it. However, we must still do what is morally right, as stated in Romans 8. This is where the distinction of the “Moral law” and the “Ceremonial law” comes from. They aren’t distinctly written in the bible, but the concept is there. Morality is what we should still follow, and the ceremonial law we need not.