Now are we sure that thou knowest ... - Their difficulty had been to understand what was the meaning of his declaration in John 16:16. About this they conversed among themselves, John 16:17-19. It is evident that they had not mentioned their difficulty to him, and that he had not even heard their conversation among themselves, John 16:19. When, therefore, by his answers to them John 16:20-28, he showed that he clearly understood their doubts; and when he gave them an answer so satisfactory without their having inquired of him, it satisfied them that he knew the heart, and that he assuredly came from God. They were convinced that there was" no need that any man should ask him," or propose his difficulties to him, since he knew them all and could answer them.

Now are we sure that thou knowest all things - Is not the following the meaning of the disciples? We believe that thou art not only the Messiah who camest out from God, but that thou art that God who searchest the heart and triest the reins, and needest not to be asked in order to make thee acquainted with the necessities of thy creatures; for thou perfectly knowest their wants, and art infinitely disposed to relieve them.

Now are we sure that thou knowest all things,.... Not only all men, but all things, even the secrets of men's hearts, of which the apostles had now a convincing proof; for whereas Christ had delivered some expressions, John 16:16; which they did not understand, and were desirous to ask him the meaning of, John 16:19; which he knowing, being God omniscient, prevents their putting the question to him, and enters upon a discourse, in which he so clearly explained what they wanted to be informed of, without their asking him, that they were fully assured that he must know all things;

and, as they add,

needest not that any man should ask thee: the meaning is, that should Christ deliver anything not so intelligible to any of his audience, and they were desirous of knowing the sense of it, there would be no need of putting the question in form to him, since he is privy to the first motion of desire rising up in the mind; and can, and will, if he thinks fit, explain himself on such an head, to the satisfaction of the person, without ever asking him; at least there is no need of putting the question to make him acquainted with his desire, this being before known unto him. By this we believe that thou camest forth from God; was the true Messiah, and had his mission and commission from God, as such; doubtless they believed this before, but this instance of Christ's omniscience was a strengthening proof of it. So Nathanael, by Christ's saying to him, that before Philip called him, and when he was under the fig tree, he saw him when he thought no eye did but an omniscient one; it laid him under such full convictions of him, as at once to acknowledge him the Son of God, the King of Israel. This is one of the signs and characters of the Messiah with the Jews, that he should have a discerning spirit of men and things, according to Isaiah 11:3 (c).

(c) T. Bab. Sanhedrin, fol. 93. 2.

We are sure (οἴδαμεν)

Better, as Rev., we know.

By this (ἐν τούτῳ)

Literally, in this. Compare 1 John 2:3, 1 John 2:5; 1 John 3:16, 1 John 3:19, 1 John 3:24; 1 John 4:9, 1 John 4:10, 1 John 4:13, 1 John 4:17; 1 John 5:2.

Now are we sure that thou knowest all things, and needest not that any man should ask thee: by this we believe that thou camest forth from God.

16:30 Thou knowest all things - Even our hearts. Although no question is asked thee, yet thou answerest the thoughts of every one. By this we believe that thou camest forth from God - They, as it were, echo back the words which he had spoken in John 16:27, implying, We believe in God; we believe also in thee.

16:28-33 Here is a plain declaration of Christ's coming from the Father, and his return to him. The Redeemer, in his entrance, was God manifest in the flesh, and in his departure was received up into glory. By this saying the disciples improved in knowledge. Also in faith; Now are we sure. Alas! they knew not their own weakness. The Divine nature did not desert the human nature, but supported it, and put comfort and value into Christ's sufferings. And while we have God's favourable presence, we are happy, and ought to be easy, though all the world forsake us. Peace in Christ is the only true peace, in him alone believers have it. Through him we have peace with God, and so in him we have peace in our own minds. We ought to be encouraged, because Christ has overcome the world before us. But while we think we stand, let us take heed lest we fall. We know not how we should act if brought into temptation; let us watch and pray without ceasing, that we may not be left to ourselves.