Jesus entered the temple courts, and, while he was teaching, the chief priests and the elders of the people came to him. "By what authority1 are you doing these things?" they asked. "And who gave you this authority?"
References for Matthew 21:23
Jesus replied, "I will also ask you one question. If you answer me, I will tell you by what authority I am doing these things.
John's baptism--where did it come from? Was it from heaven, or from men?" They discussed it among themselves and said, "If we say, 'From heaven,' he will ask, 'Then why didn't you believe him?'
But if we say, 'From men'--we are afraid of the people, for they all hold that John was a prophet."2
References for Matthew 21:26
So they answered Jesus, "We don't know." Then he said, "Neither will I tell you by what authority I am doing these things.