A.T. Robertson Commentary John 13:8

"Peter saith unto him, Thou shalt never wash my feet. Jesus answered him, If I wash thee not, thou hast no part with me." — John 13:8 (ASV)

Thou shalt never wash my feet (ου μη νιψηις μου τους ποδας εις τον αιωνα). Strong double negative ου μη with first aorist active subjunctive of νιπτω with εις τον αιωνα (for ever) added and μου (my) made emphatic by position. Peter's sudden humility should settle the issue, he felt.

If I wash thee not (εαν μη νιψω σε). Third-class condition with εαν μη (negative). Jesus picks up the challenge of Peter whose act amounted to irreverence and want of confidence. "The first condition of discipleship is self-surrender" (Westcott). So "Jesus, waiting with the basin" (Dods), concludes.

Thou hast no part with me (ουκ εχεις μερος μετ' εμου). Not simply here at the supper with its fellowship, but in the deeper sense of mystic fellowship as Peter was quick to see. Jesus does not make foot-washing essential to spiritual fellowship, but simply tests Peter's real pride and mock-humility by this symbol of fellowship.