A.T. Robertson Commentary John 13:7

"Jesus answered and said unto him, What I do thou knowest not now; but thou shalt understand hereafter." — John 13:7 (ASV)

I... thou (εγω... συ). Jesus repeats the pronouns used by Peter in similar contrast.

Not now (ουκ αρτ). Just now αρτ means (9:19,25). Used again by Jesus (verse 33) and Peter (verse 37).

But thou shalt understand hereafter (γνωση δε μετα ταυτα). Future middle of γινωσκω (instead of the verb οιδα) to know by experience. "Thou shalt learn after these things," even if slowly.