Hearing does not obligate anyone to a defunct covenant.
I never said it did. God's standard of a righteous and holy conduct exist independently of any contract to obey it. Someone who was a member of the Old Covenant who committed murder would be in violation of both their covenant and of God's righteous and holy standard of conduct. Someone who are not a member of the Old Covenant who committed murder would not be in violation of that contract, but would still be in violation of God's righteous and holy standard, so even if God had made no covenants with us, it would still be good to have a righteous and holy conduct in accordance with God's righteous and holy standard. Jesus was perfectly in obedience to God's holy and righteous standard and if we hear his words, then we should follow his example.
Jesus nor anyone else in the NT says keep the Sabbath.
bugkiller
We are commanded to love the Lord our God with all of our heart, soul, strength, and mind and love our neighbor as ourselves. Jesus said that the rest of the laws hang on those two commands, so they are examples of how we are to express our love. The law in God's instruction for how to live righteously, so when the NT says we should practice righteousness, that includes keeping the Sabbath. When Paul said that all Scripture is useful for training in righteousness, that again included keeping the Sabbath. When he said that it equips us to do every good work and that we are created in Christ to do good works, that includes the Sabbath.
As followers of God, it should be a given that we should follow His commands, and as followers of Jesus, it should be a given that we should imitate his example of obedience, so I see no good reason to think that Jesus or any of the NT authors thought that only the commands they repeated were important to keep. Throughout most of the OT, the Israelites were going astray and God consistently wanted them to turn their hearts back to Him and keep His commands. It's almost as if God had an expectation for how His chosen people should behave. The problem was not with the Old Covenant, but with their disobedience. So God solved the problem by making a New Covenant where He would write His instructions on our hearts, he send Jesus to set us free from disobedience to His instructions, and He sent the Spirit to lead us in obedience to His instructions. So now that we are counted among God's chosen people, we should live in obedience to God's instructions. It does not follow at all from this that God would suddenly stop caring whether His chosen people followed His instructions.
