John Calvin on John 1:24

24. Were of the Pharisees. He says that they were Pharisees, who at that time held the highest rank in the Church; and he says so in order to inform us, that they were not some contemptible persons of the order of the Levites, but men clothed with authority. This is the reason why they raise a question about his baptism. Ordinary ministers would have been satisfied with any kind of answer; but those men, because they cannot draw from John what they desired, accuse him of rashness for venturing to introduce a new religious observance.