John 3:25

ἐγένετο οὖν ζήτησις … There arose therefore that is, in consequence of the proximity of these two baptisms on the part of John's disciples [ἐκ, cf. Herod. John 3:21 and Dionys. Hal. viii. p. 556] a questioning, or discussion, with a Jew about purifying, that is, generally, including the relation of those two baptisms to one another, and to the Jewish washings, and the significance of each. The trend of the discussion may be gathered from the complaint to the Baptist, John 3:26. As the discussion was begun by the disciples of John, it would seem as if they had challenged the Jew for seeking baptism from Jesus. For their complaint is (John 3:26) Ῥαββί … πρὸς αὐτόν. That Jesus should baptise as well as John they could not understand. Really, the difficulty is that Jesus should have allowed John to go on baptising, and that John should not himself have professed discipleship of Jesus. But so long as John saw that men were led by his preaching to accept the Messiah he might well believe that he served Christ better thus than by following in His train.