One of the most common errors on this subject and many other subjects is that somehow the New Testament represents a replacement law. A new Sinai, as it were. As if somehow God's Law given in
Exodus 20 etc somehow 'expired', everything came to a screeching halt, and the New Testament had to be written with a completely new set of commands, replacing all the old commands.
Thus, 'if it is not repeated in the New Testament it is abolished' is a common belief and saying. People believe and think that any commandment of God not repeated in the New Testament scripture is somehow done away with. But where does such an idea come from? It doesn't come from the Old Testament, that is certain. And it doesn't come from the New Testament either because no such statement or declaration can be found therein.
People take the New Testament and make it a new 'law'. The New Testament does not contain a replacement Torah, it provides (indeed, it IS) the proper and correct INTERPRETATION, APPLICATION, and UNDERSTANDING of the Law of God. In other words, 'the fulfillment of the law'. Jesus said he came NOT TO DESTROY but to FULFILL. This means that the fulfillment of the law does NOT DESTROY IT or abolish it or make it 'go away'. It fulfills it, it brings it to its fullest measure.
Jesus is the Rabbi giving the proper halachah or interpretation and application of the torah, to put it in Jewish terms.