Ezekiel 37:1-14; Psalm 106(107):2-9; Matthew 22:34-40
The Pharisees Challenge Jesus with a somewhat technical question - which is the greatest commandment? A trap really, as all the commandments are great. Jesus responds with a technical answer, quoting Deuteronomy - "Hear, O Israel: the Lord your God is one Lord; and you shall love the Lord your God with all your heart, and with all your soul, and with all your might." This text comes shortly after Moses is given the ten commandments and does re-inforce the first as the most important.
Perhaps Jesus also recited the rest of that part of Deuteronomy - perhaps he did not need to as the scripture should have been well known to the Pharisees.
"And these words which I command you this day shall be upon your heart; and you shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise." This is said by all those who recite Compline (night prayer) on every Saturday of the year. It extends the law from merely a code of behaviour, into a way of being - and that is the key to understanding the call of Jesus to the Pharisees, and to us.
The Gospel impels us to live a life of Love - the Apostle Paul gives us a fine and well known definition of what Love means in 1 Corinthians 13.