By what authority

“So they answered, ‘We don’t know where it was from.’ Jesus said, ‘Neither will I tell you by what authority I am doing these things.’” Luke 20:7-8
In Luke 20:1-8 we see the Pharisees challenging Jesus, saying, “Tell us by what authority You are doing these things” (Luke 20:2). Here was this man, who hadn’t gone to their seminary, who was drawing crowds to hear His teaching and making them jealous. I love Jesus’ response here. Instead of giving them a direct answer, He poses them a question: “John’s baptism – was it from heaven, or from men?” (Luke 20:4).
Now they were the ones in a tight spot. They wanted to say, ‘From men’, because they didn’t like John the Baptist either, but they knew that if they said this (and thus denying that his ministry was from God), this would go against the popular opinion of the people. If they said, ‘From heaven’, then Jesus would start questioning them as to why they had not welcomed him as a true prophet of God. So instead they decide to answer with something non-committal: “We don’t know.”
This wasn’t true. They did know; they just didn’t want to say. So, since they refused to say, then Jesus responds in kind and refuses to give them an answer, instead saying, “Neither will I tell you”. He knows that they know the answer, and He makes sure that they know that He knows that they know.