(33) We cannot tell.--Better, as also in Matthew 21:27, We do not know. The repetition of the verb "tell" in the English, gives an unreal emphasis which is not in the Greek. The real stress lies on the pronoun "I."
Verse 33. - We know not. They had seen the life of John. They had heard his holy and Divine teaching. They were witnesses to his death for the truth; and yet they lie. They might have said," We think it imprudent or inexpedient to say;" but for this they had not sufficient moral courage. Neither tell I you by what authority I do these things. You will not answer my question; neither will I therefore answer yours; because your answer to mine is the answer to your own. "He thus shows," says St. Jerome, "that they knew, but would not answer; and that he knew, but did not speak, because they were silent as to what they knew." Our Lord did thus but mete out to them the measure which they meted to him.
11:27-33 Our Saviour shows how near akin his doctrine and baptism were to those of John; they had the same design and tendency, to bring in the gospel kingdom. These elders did not deserve to be taught; for it was plain that they contended not for truth, but victory: nor did he need to tell them; for the works he did, told them plainly he had authority from God; since no man could do the miracles which he did, unless God were with him.
we cannot tell: they could, if they would, but they did not care to tell; they knew if they did, they should expose themselves one way or other:
and Jesus answering, saith unto them, neither do I tell you by what authority I do these things; See Gill on Matthew 21:27.