John 13:8

Peter saith unto him, thou shall never wash my feet
Before he had behaved with modesty, but now with obstinacy and perverseness; and though these expressions might arise from great reverence to Christ, yet they were wrong and rashly spoken. Peter ought to have been satisfied with Christ's reply, and have submitted, since though he then did not know the reason of such surprising conduct, he should hereafter. In order therefore to bring him to a compliance,

Jesus answered him, if I wash thee not, thou hast no part with me;
he does not say, if I wash not thy feet, but thee, meaning not with water, but with his blood, and by his Spirit; for Christ uses the word wash here, not literally, but in a mystical and figurative sense, and takes an occasion, as he sometimes does, from things natural, to discourse of things spiritual: moreover, he does not say, thou hast no part "in" me, but thou hast no part "with" me, that is, no fellowship and communion with me; see ( 2 Corinthians 6:14 2 Corinthians 6:15 ) ; and it is as if he should say, Peter, if I had not washed thee with the washing of regeneration by my Spirit, and if I should not shed my blood for thee, and wash thee in it from thy sins, sad would be thy case; thou couldest have no communion with me in this world, nor any part and portion with me in the heavenly inheritance hereafter. Hence it may be observed, that unless a man is washed by Christ, he can have no part with him in this, or the other world. God's elect have a part, an interest in Christ through eternal, electing, and covenant grace, and in consequence of this are washed by Christ both with his blood, and with the washing of regeneration: and this is done in order that they may have a part with Christ, spiritual fellowship with him now, and possess with him the undefiled inheritance, when time shall be no more.