Christ never said the 10 Commandments were done away with. In fact, He expanded and deepened the meaning. Here's an example:
"You have heard that it was said, ‘Do not commit adultery.’ But I tell you that anyone who looks at a woman to lust after her has already committed adultery with her in his heart." Matt. 5:27,28
He also had to show how the Sabbath was to be kept. He showed what you can do, that the Sabbath can be a delight, and not a burden.
Nowhere does He say any of the 10 Commandments are done away with. He adds "New Commandments" which are not new at all.
Love the Lord thy God :
Love thy neighbor:
Leviticus 19:18 - Thou shalt not avenge, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I am the LORD.
Also, the first of the "New Commandments" cover the first four of the Decalogue, and the second "New Commandment" covers the last 6.