The Unchanging Law
This verse demonstrates the spiritual law, that set of laws that reality operates upon, is eternal - from the beginning until way after the end - was what Jesus was teaching us. It was a couple of decades into my reading the Bible that I ever caught on to the fact that Jesus was quoting the Old Testament when He responded to the scribes. I don't know why - it's pretty obviously stated along with the Shema. I suppose I always understood it to be some new point Jesus was making - like the "adultery in your heart" thing. So it was an eye opener when I came across this in Leviticus.