Albert Barnes' Notes on the Whole Bible - John 13:8
Thou shalt never wash my feet - This was a decided and firm expression of his reverence for his Master, and yet it was improper. Jesus had just declared that it had a meaning, and that he ought to submit to it. We should yield to all the plain and positive requirements of God, even if we cannot now see how obedience would promote his glory.If I wash thee not - This had immediate reference to the act of washing his feet; and it denotes that if Peter had not so much confidence in him as to... read more
The Pulpit Commentary - John 13:7-8
Jesus answered and said to him, That which I am doing thou knowest not now —thou hast not absolute knowledge of, thou hast not seen through as yet; but after these things , afterwards when I shall have completed my present undertaking, thou ( γνώσῃ ) shalt come by clear proof and full discovery and intimate acquaintance to understand . This is sometimes referred to the subsequent illumination of the Holy Spirit, or even to the higher life of the future world (Luthardt), but the... read more