John answered them, saying, I baptize with water: but there standeth one among you, whom ye know not;
John answered them, saying, I baptize with water - with water only; the higher, internal, baptism with the Holy Spirit being the exclusive prerogative of his Master. (See the note at Matthew 3:11.)
But there standeth one among you, whom ye know not. This must have been spoken after Christ's Baptism, and probably almost immediately after it.