Matthew 7:12 Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets.
Matthew 22:39 And the second is like unto it, Thou shalt love thy neighbour as thyself.
Matthew 22:40 On these two commandments hang all the law and the prophets.
This new commandment you think is a "new law" is about love, and loving another is not a new concept.
All the law and the prophets hang on LOVE.
"A new commandment" is not "a new law" is it? I request that you look through
Hebrews 8 which you brought up to see if it says God would make a new law.
Jer 31:31 Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah;
Heb 8:7 For if that first covenant had been faultless, then should no place have been sought for the second.
Was not the first covenant the written commandments on stone tablets?
What was faulty was the covenant and NOT the law, for if you believe that the law was faulty, you'll have to call God a lier which he is not.