A.T. Robertson Commentary John 2:21

"But he spake of the temple of his body." — John 2:21 (ASV)

But he spake of the temple of his body (εκεινος δε ελεγεν περ του ναου του σωματος αυτου). Emphatic he (εκεινος) and imperfect tense (he had been speaking). This is John's view as he looks back at it, not what he understood when Jesus spoke the words.