Mark 11:24
Amen I say to you, whatsoever you ask when you pray, believe that you shall receive, and it shall be done to you.
Denzinger
2276: The Divine Office, the Public Prayer of the Church
From the Encyclical, "Ad catholici sacerdotii," December 20, 1935
Finally, the priest in this matter, also, performing the work of Jesus Christ, who “passed the whole night in the prayer of God” [Luke 6:12], and “always lived to make intercession for us” [Heb. 7:25], is by office the intercessor with God for all; it is among his mandates to offer not only the proper and true sacrifice of the altar in the name of the Church to the heavenly Godhead, but also “the sacrifice of praise” [Ps. 49:14] and common prayers; he, indeed, by the psalms, the supplications, and the canticles, which are borrowed in great measure from Sacred Scripture, daily, again and again discharges the duty of adoration due to God, and he performs the necessary office of such an accomplishment for men.…
If private supplication is so powerful because of the solemn and great promises given by Jesus Christ [Matt. 7:7-11; Mark 11:23; Luke 11:9-13], then the prayers, which are uttered in the Office in the name of the Church, the beloved spouse of the Redeemer, without doubt enjoy greater force and virtue.
Catena Aurea
19. And when even was come, He went out of the city. 20. And in the morning, as they passed by, they saw the fig tree dried up from the roots. 21. And Peter calling to remembrance saith unto Him, "Master, behold, the fig tree which Thou cursedst is withered away." 22. And Jesus answering saith unto them, "Have faith in God. 23. For verily I say unto you, That whosoever shall say unto this mountain, Be thou removed, and be thou cast into the sea; and shall not doubt in his heart, but shall believe that those things which he saith. 24. Therefore, I say unto you, What things soever ye desire, when ye pray, believe that ye receive them, and ye shall have them. 25. And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses. 26. But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses."
Pseudo-Jerome: The Lord, leaving darkness behind Him in the hearts of the Jews, went out, as the sun, from that city to another which is well-disposed and obedient. And this is what is meant, when it is said, “And when even was come, He went out of the city.” But the sun sets in one place, rises in another, for the light, taken from the Scribes, shines in the Apostles; wherefore He returns into the city; on which account there is added, “And in the morning, as they passed by, (that is, going into the city,) they saw the fig tree dried up from the root.”
Theophylact: The greatness of the miracle appears in the drying up so juicy and green a tree. But though Matthew says that the fig tree was at once dried up, and that the disciples on seeing it wondered, there is no reason for perplexity, though Mark now says, that the disciples saw the fig tree dried up on the morrow; for what Matthew says must be understood to mean that they did not see it at once, but on the next day.
Augustine, de Con. Evan, ii, 68: The meaning is not that it dried up at the time, when they saw it, but immediately after the word of the Lord; for they saw it, not beginning to dry up, but completely dried up; and they thus understood that it had withered immediately after our Lord spoke.
Pseudo-Jerome: Now the fig tree withered from the roots is the synagogue withered from Cain, and the rest, from whom all the blood from Abel up to Zechariah is required.
Bede: Further, the fig tree was dried up from the roots to shew that the nation was impious not only for a time and in part, and was to be smitten forever, not merely to be afflicted by the attacks of nations from without and then to be freed, as had often been done; or else it was dried up from the roots, to shew that is was stripped not only of the external favour of man, but altogether of the favour of heaven within it; for it lost both its life in heaven, and its country on earth.
Pseudo-Jerome: Peter perceives the dry root, which is cut off, and has been replaced by the beautiful and fruitful olive, called by the Lord.
Wherefore it goes on: “And Peter calling to remembrance saith unto Him, Master, behold, the fig tree which Thou cursedst is withered away.”
Chrys.: The wonder of the disciples was the consequence of imperfect faith, for this was no great thing for God to do; since then they did not clearly know His power, their ignorance made them break out into wonder. And therefore it is added, “And Jesus answering saith unto them, Have faith in God. For verily I say unto you, That whosoever shall say unto this mountain,” &c. That is; Thou shalt not only be able to dry up a tree, but also to change a mountain by they command and order.
Theophylact: Consider the Divine mercy, how it confers on us, if we approach Him in faith, the power of miracles, which He Himself possesses by nature, so that we should be able even to change mountains.
Bede: The Gentiles, who have attacked the Church, are in the habit of objecting to us, that we have never had full faith in God, for we have never been able to change mountains. It could, however, be done, if necessity called for it, as once we read that it was done by the prayers of the blessed Father Gregory of Neocaesarea, Bishop of Pontus, by which a mountain left as much space of ground for the inhabitants of a city as they wanted.
Chrys.: Or else, as He did not dry up the fig tree for its own sake, but for a sign that Jerusalem should come to destruction, in order to shew His power, in the same way we must also understand the promise concerning the mountain, though a removal of this sort is not impossible with God.
Pseudo-Jerome: Christ then who is the mountain, which grew from the stone, cut out without hands, is taken up and cast into the sea, when the Apostles with justice say, Let us turn ourselves to other nations, [Acts 13:46] since ye judged yourselves unworthy of hearing the word of God.
Bede: Or else, because the devil is often on account of his pride called by the name of a mountain, this mountain, at the command of those who are strong in the faith, is taken up from the earth and cast into the sea, whenever, at the preaching of the word of God by the holy doctors, the unclean spirit is expelled from the hearts of those who are fore-ordained to life, and is allowed to exert the tyranny of his power over the troubled and embittered souls of the faithless. At which time, he rages the more fiercely, the more he grieves at being turned away from hurting the faithful.
It goes on: “Therefore I say unto you, What things soever ye desire, when ye pray, believe that ye receive them, and ye shall have them.”
Theophylact: For whosoever sincerely believes evidently lifts up his heart to God, and is joined to Him, and his burning heart feels sure that he has received what he asked for, which he who has experienced will understand; and those persons appear to me to experience this, who attend to the measure and the manner of their prayers. For this reason the Lord says, “Ye shall receive whatsoever ye ask in faith;” for he who believes that he is altogether in the hands of God, and interceding with tears, feels that he as it were has hold of the feet of the Lord in prayer, he shall receive what he has rightly asked for. Again, would you in another way receive what you ask for? Forgive your brother, if he has in any way sinned against you; this is also what is added: “And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses.”
Pseudo-Jerome: Mark has, as he is wont, expressed seven verses of the Lord’s prayer in one prayer. But what can he, whose sins are all forgiven, require more, save that he may persevere in what has been granted unto him.
Bede: But we must observe that there is a difference in those who pray; he who has perfect faith, which worketh by love, can by his prayer or even his command remove spiritual mountains, as Paul did with Elymas the sorcerer. But let those who are unable to mount up to such a height of perfection pray that their sins should be forgiven them, and they shall obtain what they pray for, provided that they themselves first forgive those who have sinned against them. If however they disdain to do this, not only shall they be unable to perform miracles by their prayers, but they shall not even be able to obtain pardon for their sins, which is implied in what follows; “But if ye do not forgive, neither will your Father which is in heaven forgive your trespasses.”