The words spoken from heaven and heard out of the fire on Mt. Sinai, the words spoken by the angel of the Lord, if heard mixed with faith, as it was with a few, the everlasting (new) covenant would come through the faith mixed with the words.
When the Lord gave Abraham the work of circumcision, it was heard mixed with faith and thus it was an everlasting covenant through the gift of faith mixed with the words of duty.
In all communications, from the least duty to the greatest duty, faith is the gift of God by which grace (new/everlasting covenant) operates unto salvation from sin unto righteousness.
The duty is our servant status. Faith and grace are the gifts of the family membership.
New testament words are heard under the old covenant principle if these words are not mixed with the gift of faith through which grace operates with the operation of God's liberty that is in Jesus Christ.
Ex 20:1-3
And God spake all these words, saying,
2 I am the LORD thy God, which have brought thee out of the land of Egypt, out of the house of bondage.
3 Thou shalt have no other gods before me. KJV
When we hear this mixed with faith/grace, we are then prepared to hear the next principle.
None of us start with faith and grace. We start with the authority of the speaker and consent unto duty because of the power of the authority of the speaker, whether it be human or angel. This is where all children begin and it is not to be despised or condemned. This is where Abram began under his father, Terah.
We only judge unto the condemnation of others when we have grown in human prowess and desires but not mixed with faith and grace. The words then become hard as stone in our thoughts. We do not hear them with wisdom and understanding that comes through being mixed with faith and grace.
The same experience comes in connection with the words of the New Testament. The words become hardened in our thoughts and we strive about the meaning of the words, which does not edify the Body of Jesus Christ. This striving is the wisdom of conceit, and leads us to despise the simple and not accept the grace of God in the ministry of Moses as the moonlight of grace. Moonlight is useful. Sunlight is greater.
Joe