According to Mark (7.6), Jesus initiates his response with a quotation from Isaiah. Matthew handles the confrontation differently, by introducing first Jesus’ fierce denunciation of the Pharisees, and later he introduces the quotation (verses 8-9). To answer a question with a question (verse 3) was a typical method of debate among the Jewish teachers, and Jesus employs this mode of argument to show how the Pharisees had disobeyed God’s commands in order to follow their own teaching.
This question is intended to imitate the form of the question which they asked of Jesus, and so translators should treat why in the same way they did in the previous verse, either as a request for information or as an accusation.
Transgress is the same verb here as in verse 2.
The commandment of God may be more clearly phrased as “what God commanded us to do” or “what our Scriptures tell us that God commanded us to do.”
For the sake of your tradition (Good News Translation “and follow your own teaching”) may be translated “in order to do what you teach” or “… to do what you say God wants his people to do.”
Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .