The Pharisees had to try to show up the Saducees by silencing Jesus since Jesus had silenced the latter. The Pharisees felt that they could only do this by setting a verbal trap for Him. And so they had one of their brightest and best legal scholars (highly skilled in the Law of Moses) ask Him which commandment was the greatest. Jesus didn’t hesitate, but quoted from Deuteronomy 6:5. But He didn’t stop there, He also stated what the second greatest law was by quoting from Leviticus 19:18. Note carefully that both of these are within the Mosaic Law (Genesis through Deuteronomy). He then said that the entirety of the Law depends upon these two commandments.
Before they could recover from their surprise at His wisdom, He then, as was His privilege in such debate, asked them a question based on Psalm 110:1. They were unable to answer His question and therefore, by the rules of debate, could no longer question Him.
It would behoove us to carefully contemplate the words of these verses that Jesus quoted. His wisdom is not just for baffling the ungodly scribes, but more importantly for the life of His people as well. Complete and whole hearted obedience to His commands is the beginning of a life well lived!