John 13:7

What I do thou knowest not now, etc. - As if our Lord had said, Permit me to do it now, and I will shortly explain to you the nature of this action, and my motives for doing it.

Thou shalt know hereafter - Μετα ταυτα, after this business is finished. And so we find he explained the whole to them, as soon as he had finished the washing: see John 13:12-17. I cannot think that this refers to any particular instruction received on this head after the day of pentecost, as some have conjectured.

Thou knowest not now - Though he saw the action of Jesus, yet he did not fully understand the design of it. It was a symbolical action, inculcating a lesson of humility, and intended to teach it to them in such a manner that it would be impossible for them ever to forget it. Had he simply commanded them to be humble, it would have been far less forcible and impressive than when they saw him actually performing the office of a servant.

Shalt know hereafter - Jesus at that time partially explained it John 13:14-15; but he was teaching them by this expressive act a lesson which they would continue to learn all their lives. Every day they would see more and more the necessity of humility and of kindness to each other, and would see that they were the servants of Christ and of the church, and ought not to aspire to honors and offices, but to be willing to perform the humblest service to benefit the world. And we may remark here that God often does things which we do not fully understand now, but which we may hereafter. He often afflicts us; he disappoints us; he frustrates our plans. Why it is we do not know now, but we yet shall learn that it was for our good, and designed to teach us some important lesson of humility and piety. So he will, in heaven, scatter all doubts, remove all difficulties, and show us the reason of the whole of his mysterious dealings in his leading us in the way to our future rest. We ought also, in view of this, to submit ourselves to him; to hush every murmur, and to believe that he does all things well. It is one evidence of piety when we are willing to receive affliction at the hand of God, the reason of which we cannot see, content with the belief that we may see it hereafter; or, even if we never do, still having so much confidence in God as to believe that what He does is right.

13:7 What I do thou knowest not now; but thou shalt know hereafter - We do not now know perfectly any of his works, either of creation, providence, or grace. It is enough that we can love and obey now, and that we shall know hereafter.