Matthew 21:20

Now in order to convey this truth the Lord acted prophetically. By this I mean that in reference to the fig tree, it was not his will merely to exhibit a miracle but rather through this sign to convey an intimation of that which was to come. He often taught and persuaded us by such means. So even when our wills resist, he persuades us and brings us to faith.We first ask how was it the tree's fault that it had no fruit? Even if it had no fruit in its proper season, its season of mature fruit, still the tree would bear no fault. For the tree is without sense and reason, so it could not be blamed. But to this perplexity is added another, which we read in the narrative of the other Evangelist who expressly mentions this: "It was not the time for that fruit." For this was the time when the fig tree was just shooting forth its tender leaves, which come, as we know, long before the fruit. This sequence has a spiritual meaning. The time for fruit was soon coming with the day of the Lord's Passion, which was at hand. And so to make this clear, the Evangelist, to his credit, notes that "the time of figs was not yet." So then, if it was only a miracle that was being demonstrated and not something to be prophetically prefigured, it would have been much more worthy of the clemency and mercy of the Lord if he had found a withered tree and restored it to life. This would seem more in accord with his healing of the sick, cleansing lepers and raising the dead. But to the contrary, as though against the ordinary rule of his charity, he found a green tree, not yet bearing fruit, even before its fruit-bearing season but still awaiting the hope of fruit, and what does he do? He withers it straight away! This is a prophetic anticipation of things soon to come, by which he in effect says to us: "I have no delight in the withering away of this tree. […]

(de Cons. Ev. ii. 68.) It must be considered that Mark relates the wonder of the disciples at the withering of the tree, and the answer of the Lord concerning faith, to have been not on the day following the cursing of the tree, but on the third day after; and that on the second day Mark relates the casting of the merchants out of the Temple, which he had omitted on the first day. On the second day then he says that He went forth out of the city in the evening, and that as they passed by in the morning, the disciples then saw that the fig tree was withered. But Matthew speaks as though all this had been done on the day following. This must be so taken as that when Matthew, having related that the fig tree was dried up, adds immediately, omitting all the events of the second day, And when the disciples saw if, they marvelled, he yet meant that it was on another day that they marvelled. For the tree must be supposed to have withered at the time it was cursed, not at the time they saw it. For they did not see it withering, but when it was withered, and by that they understood that it had withered immediately upon the Lord's words.

But if the Lord come seeking fruit with temptations, and one be found having nought of righteousness but only a profession of faith, which is leaves without fruit, he is soon withered, losing even his seeming faith; and every disciple makes this fig tree to wither, by making it be seen that he is void of Christ, as Peter said to Simon, Thy heart is not right in the sight of God (Acts 8:21.) For it is better that a deceitful fig tree which is thought to be alive, yet brings forth no fruit, should be withered up at the word of Christ's disciples, than that by an imposture it should steal aawy innocent hearts. Also there is in every unbeliever a mountain great in proportion to his unbelief, which is removed by the words of Christ's disciples.

Of the many miracles which the Lord performed, all were done to do good, for He performed no miracles of chastisement. Therefore, lest anyone think that He is unable to chastise, here He shows this power as well, not applied to men but to a …

"And the disciples seeing it wondered." Here first the wonder is presented; secondly, the satisfaction of the wonder. He says "and the disciples seeing it wondered." Just as men wonder when they see a spirit that seems good, and it quickly withers, so they wondered …