Jesus said that the whole of the Old Testament, (the Law, the Prophets, and the Writings as they were often described) could be summarised in one sentence "Do to others whatever you would like them to do to you" (Matthew 7:12, NLT). In the Old Testament Micah said something very similar; "He has told you, O man, what is good; and what does the LORD require of you but to do justice, and to love kindness, and to walk humbly with your God?" (Micah 6:8, ESV). There is moral standard, gospel, and how to live embedded within the summary of Jesus in Matthew 7:12. Watch: https://youtu.be/6obHyHi_nI8