A.T. Robertson Commentary John 1:30

"This is he of whom I said, After me cometh a man who is become before me: for he was before me." — John 1:30 (ASV)

Of whom (υπερ ου). Not περ, but υπερ. "On behalf of whom." John points to Jesus as he speaks: "This is he." There he is. See verse 15 for discussion of these words of John.