And he said to them. This reproof appears to be too harsh and severe for a weak man such as this was; but whoever attends to all the circumstances will have no difficulty in perceiving that our Lord had good reason for rebuking so sharply those on whom he had long bestowed labor to little purpose, and almost without any fruit. For it ought to be observed, that; what is here said was not confined to these two persons, but, as a reproof of a common fault, was intended to be conveyed by their lips to the rest of their companions. So frequently had Christ forewarned them of his death -- so frequently had he even discoursed about a new and spiritual life, and confirmed his doctrine by the inspired statements of the prophets -- that he would seem to have spoken to the deaf, or rather to blocks and stones; for they are struck with such horror at his death, that they know not to what hand to turn. This hesitation, therefore, he justly attributes to folly, and assigns as the reason of it their carelessness in not having been more ready to believe. Nor does he only reprove them because, while they had the best Teacher, they were dull and slow to learn, but because they had not attended to the instructions of the Prophets; as if he had said, that their insensibility admitted of no excuse, because it was owing to themselves alone, since the doctrine of the Prophets was abundantly clear, and had been fully expounded to them. In like manner, the greater part of men, at the present day, remain in ignorance through their own fault, because they are obstinate, and refuse to be instructed. But let us observe that Christ, perceiving that his disciples are excessively sluggish; commences with reproof, in order to arouse them; for this is the way in which we must subdue those whom we have found to be hardened or indolent.

O fools - The word "fool" sometimes is a term of reproach denoting "wickedness." In this sense we are forbidden to employ it in addressing another, Matthew 5:22. That, however, is a different word in the Greek from the one which occurs here. The one there used implies contempt, but the one employed in this place denotes "weakness or dulness." He reproached them for not seeing what he had himself so clearly predicted, and what had been foretold by the prophets. The word used in the original does not imply as much "reproach" as the word "fool" does among us. It was not an expression of "contempt;" it was an expression denoting merely that they were "thoughtless," and that they did not properly "attend to" the evidence that he must die and rise again.
Slow of heart to believe - Not quick to perceive. Dull of learning. They had suffered their previous opinions and prejudices to prevent their seeing the evidence that he must die and rise from the dead.
All that the prophets have spoken - Respecting the character and sufferings of the Messiah. See the notes at Luke 24:27.

O fools and slow of heart to believe - Inconsiderate men, justly termed such, because they had not properly attended to the description given of the Messiah by the prophets, nor to his teaching and miracles, as proofs that He alone was the person they described.
Slow of heart - Backward, not easy to be persuaded of the truth, always giving way to doubtfulness and distrust. This very imperfection in them is a strong evidence of the truth of the doctrine which they afterwards believed, and proclaimed to the world. Had they not had the fullest assurance of these things, they never would have credited them; and it is no small honor to the new-covenant Scriptures that such persons were chosen, first, to believe them; secondly, to proclaim them in the world; and, thirdly, to die on the evidence of those truths, the blessed influence of which they felt in their own hearts, and fully exemplified in their lives.

Then he said unto them,.... That is, Jesus said unto them, as the Syriac and Persic versions read:
O fools; not in a natural sense, as if they were destitute of the common understanding of men; nor in a moral sense, as wicked men, and as they themselves had been in their unregenerate estate; nor in a way of anger and contempt, and with a design to provoke; wherefore Christ did not act contrary to his own rule, in Matthew 5:22 but because they were so void of understanding in the Scriptures, and were so very ignorant of them, and were so blind as to the knowledge of them; particularly those which concerned the sufferings and resurrection of the Messiah, being influenced by the popular prejudices of education: he therefore expresses himself with much warmth, concern, and surprise, that he should have been so long with them, and they so long under his doctrine and ministry; besides the advantages of having the Scriptures, and being conversant with them from their youth; and which they daily read, and had heard expounded, and yet were so very senseless and stupid:
and slow of heart to believe all that the prophets have spoken; that is, upon these points, concerning the sufferings of Christ, and his resurrection from the dead; and indeed, they were very slow of heart to believe, not only what the women reported from the angels, but even those of their brethren, who had seen him after he was risen; for which Christ upbraids them, Mark 16:14. Yea, one of them declared after all, that he would not believe, unless he saw the print of the nails in his hands and feet, and put his hand into it, and thrust it into his side; wherefore Christ had good reason to treat them in this sharp manner, and charge them with folly and incredulity; the Jews ought not to object to the word "fools", as unbecoming Christ, since they frequently represent God as making use of it; as for instance, it is said, (x).
"the holy blessed God said to them, "O ye fools" that are in the world, whatsoever ye do, ye do for your own necessities. ---And a little after, "O ye fools" that are in the world, he that labours on the evening of the sabbath, shall eat on the sabbath day.''
(x) T. Bab. Avoda Zara, fol. 2. 2. & 3. 1.

fools--senseless, without understanding.

O foolish men. Because "slow of heart to believe all that the prophets have spoken."

O foolish - Not understanding the designs and works of God: And slow of heart - Unready to believe what the prophets have so largely spoken.