Matthew 22:37 - Ellicott's Commentary On The Whole Bible

Thou shalt love the Lord thy God. — In St. Mark’s report (Mark 12:29) our Lord’s answer begins with the Creed of Israel (“Hear, O Israel, the Lord our God is one Lord”), and so the truth is in its right position as the foundation of the duty. It is significant (1) that the answer comes from the same chapter (Deuteronomy 6:4-5) which supplied our Lord with two out of His three answers to the Tempter (see Notes on Matthew 4:4; Matthew 4:7); and (2) that He does but repeat the answer that had been given before by the “certain lawyer” who stood up tempting Him, in Luke 10:25. In their ethical teaching the Pharisees had grasped the truth intellectually, though they did not realise it in their lives, and our Lord did not shrink, therefore, so far, from identifying His teaching with theirs. Truth was truth, even though it was held by the Pharisees and coupled with hypocrisy.