“John answered them, saying, I baptize with water: but there standeth one among you, whom ye know not;”
John 1:26 — Greek Interlinear
Church Fathers on John 1:26
The questions of the priests and Levites being answered, another mission comes from the Pharisees: And they that were sent were of the Pharisees. So far as it is allowable to form a conjecture from the discourse itself here, I should say that it was the third occasion of John’s giving his witness. Observe the mildness of the former question, so befitting the priestly and levitical character, Who are you? There is nothing arrogant or disrespectful, but only what becomes true…
Or, those very same priests and Levies were of the Pharisees, and, because they could not undermine him by blandishments, began accusing, after they had compelled him to say what he was not. And they asked him, saying, Why baptize you then, if you are not the Christ, neither Elias, neither that Prophet? As if it were an act of audacity in him to baptize, when he was neither the Christ, nor His precursor, nor His proclaimer, i.e. that Prophet.
A saint, even when perversely questioned, is never diverted from the pursuit of goodness. Thus John to the words of envy opposes the words of life: John answered them, saying, I indeed baptize with water.