First, the number 613 (the supposed number of Jewish laws in the Torah) is largely made up. They've tried to turn it into a numerology thing: "There are 365 negative commandments, corresponding to the number of days in a solar year, and 248 positive commandments, ascribed to the number of bones and significant organs in the human body." (from Wikipedia). The number 10, for "ten commandments" is also pretty subjective. Try counting them yourself. Remember, too, that the Catholics have done away with the graven images commandment. They've removed a commandment and they still call the number 10. How is that possible? (Ans: It's bullshit to begin with.)
Now, I don't know of anywhere Jesus said the Mosaic law was invalid. In Matthew 5:17, he allegedly says, "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them." Then, in 5:18, he allegedly says, "I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished." Ask your "friend" for the chapter and verse.
What's going on is that the conservative Christians in the US have decided to promote the 10C as the only part of the Old Testament that they really deem valid. This allows them to ignore wide swaths of the Bible that they find inconvenient. The irony is that Christians have long persecuted and killed them, so they clearly don't believe in "thou shalt not kill". They perpetually lie, including every lie I'm pointing out in this note. They covet the unborn children of others (for their potential future tithes). They make idols out of 10C monuments, lie about the intents and words of the founding fathers, and generally worship power. They don't believe the crap they're selling, so why should anyone else.
So, it's lies all the way down.