But six times in the Sermon on the Mount, he introduced what sounded like statements from the Hebrew Scriptures with the words: “It was said.” (Matthew 5:21, 27, 31, 33, 38, 43) Why? Because he was referring to the Scriptures as interpreted in the light of Pharisaic traditions that contradicted God’s commandments. (Deuteronomy 4:2; Matthew 15:3)

13. How does Jesus warn against even the beginning of conduct that could lead to actual murder?

¹³ Consider now the first of this series of six statements. Jesus declared: “You heard that it was said to those of ancient times, ‘You must not murder; but whoever commits a murder will be accountable to the court of justice.’ However, I say to you that everyone who continues wrathful with his brother will be accountable to the court of justice.” (Matthew 5:21, 22) Anger in the heart can lead to abusive speech and from there to condemnatory judgments, and it may ultimately lead to the act of murder itself. Prolonged anger nourished in the heart can be deadly: “Everyone who hates his brother is a manslayer.”​—1 John 3:15.