A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
mat 18:10FURTHER TEACHING ON THE SAME SUBJECT INCLUDING THE PARABLE OF THE UNMERCIFUL DEBTOR. (Mat. 18:10-35)
Take heed that ye despise--stumble.
not one of these little ones; for I say unto you, That in heaven their angels do always behold the face of my Father which is in heaven--A difficult verse; but perhaps the following may be more than an illustration:--Among men, those who nurse and rear the royal children, however humble in themselves, are allowed free entrance with their charge, and a degree of familiarity which even the highest state ministers dare not assume. Probably our Lord means that, in virtue of their charge over His disciples (Heb 1:13; Joh 1:51), the angels have errands to the throne, a welcome there, and a dear familiarity in dealing with "His Father which is in heaven," which on their own matters they could not assume.
mat 18:11For the Son of man is come to save that which was lost--or "is lost." A golden saying, once and again repeated in different forms. Here the connection seems to be, "Since the whole object and errand of the Son of man into the world is to save the lost, take heed lest, by causing offenses, ye lose the saved." That this is the idea intended we may gather from Mat 18:14.
mat 18:12How think ye? If a man have an hundred sheep, and one of them be gone astray, &c.--This is another of those pregnant sayings which our Lord uttered more than once. See on the delightful parable of the lost sheep in Luk 15:4-7. Only the object there is to show what the good Shepherd will do, when even one of His sheep is lost, to find it; here the object is to show, when found, how reluctant He is to lose it. Accordingly, it is added,
mat 18:14Even so it is not the will of your Father which is in heaven that one of these little ones should perish--How, then, can He but visit for those "offenses" which endanger the souls of these little ones?
mat 18:15Moreover, if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother, &c.--Probably our Lord had reference still to the late dispute, Who should be the greatest? After the rebuke--so gentle and captivating, yet so dignified and divine--under which they would doubtless be smarting, perhaps each would be saying, It was not I that began it, it was not I that threw out unworthy and irritating insinuations against my brethren. Be it so, says our Lord; but as such things will often arise, I will direct you how to proceed. First, Neither harbor a grudge against your offending brother, nor break forth upon him in presence of the unbelieving; but take him aside, show him his fault, and if he own and make reparation for it, you have done more service to him than even justice to yourself. Next, If this fail, take two or three to witness how just your complaint is, and how brotherly your spirit in dealing with him. Again, If this fail, bring him before the Church or congregation to which both belong. Lastly, If even this fail, regard him as no longer a brother Christian, but as one "without"--as the Jews did Gentiles and publicans.
mat 18:18Verily I say unto you, Whatsoever ye shall bind on earth shall be bound in heaven; and whatsoever ye shall loose on earth shall be loosed in heaven--Here, what had been granted but a short time before to Peter only (see on Mat 16:19) is plainly extended to all the Twelve; so that whatever it means, it means nothing peculiar to Peter, far less to his pretended successors at Rome. It has to do with admission to and rejection from the membership of the Church. But see on Joh 20:23.
mat 18:19Again I say unto you, That if two of you shall agree on earth as touching anything that they shall ask, it shall be done for them of my Father which is in heaven.
mat 18:20For where two or three are gathered together in my name--or "unto my name."
there am I in the midst of them--On this passage--so full of sublime encouragement to Christian union in action and prayer--observe, first, the connection in which it stands. Our Lord had been speaking of church meetings before which the obstinate perversity of a brother was in the last resort to be brought, and whose decision was to be final--such honor does the Lord of the Church put upon its lawful assemblies. But not these assemblies only does He deign to countenance and honor. For even two uniting to bring any matter before Him shall find that they are not alone, for My Father is with them, says Jesus. Next, observe the premium here put upon union in prayer. As this cannot exist with fewer than two, so by letting it down so low as that number, He gives the utmost conceivable encouragement to union in this exercise. But what kind of union? Not an agreement merely to pray in concert, but to pray for some definite thing. "As touching anything which they shall ask," says our Lord--anything they shall agree to ask in concert. At the same time, it is plain He had certain things at that moment in His eye, as most fitting and needful subjects for such concerted prayer. The Twelve had been "falling out by the way" about the miserable question of precedence in their Master's kingdom, and this, as it stirred their corruptions, had given rise--or at least was in danger of giving rise--to "offenses" perilous to their souls. The Lord Himself had been directing them how to deal with one another about such matters. "But now shows He unto them a more excellent way." Let them bring all such matters--yea, and everything whatsoever by which either their own loving relationship to each other, or the good of His kingdom at large, might be affected--to their Father in heaven; and if they be but agreed in petitioning Him about that thing, it shall be done for them of His Father which is in heaven. But further, it is not merely union in prayer for the same thing--for that might be with very jarring ideas of the thing to be desired--but it is to symphonious prayer, the prayer by kindred spirits, members of one family, servants of one Lord, constrained by the same love, fighting under one banner, cheered by assurances of the same victory; a living and loving union, whose voice in the divine ear is as the sound of many waters. Accordingly, what they ask "on earth" is done for them, says Jesus, "of My Father which is in heaven." Not for nothing does He say, "of MY FATHER"--not "YOUR FATHER"; as is evident from what follows: "For where two or three are gathered together unto My name"--the "My" is emphatic, "there am I in the midst of them." As His name would prove a spell to draw together many clusters of His dear disciples, so if there should be but two or three, that will attract Himself down into the midst of them; and related as He is to both the parties, the petitioners and the Petitioned--to the one on earth by the tie of His assumed flesh, and to the other in heaven by the tie of His eternal Spirit--their symphonious prayers on earth would thrill upward through Him to heaven, be carried by Him into the holiest of all, and so reach the Throne. Thus will He be the living Conductor of the prayer upward, and the answer downward.
Parable of the Unmerciful Debtor (Mat 18:21-35).
mat 18:21Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him?--In the recent dispute, Peter had probably been an object of special envy, and his forwardness in continually answering for all the rest would likely be cast up to him--and if so, probably by Judas--notwithstanding his Masters' commendations. And as such insinuations were perhaps made once and again, he wished to know how often and how long he was to stand it.
till seven times?--This being the sacred and complete number, perhaps his meaning was, Is there to be a limit at which the needful forbearance will be full?
mat 18:22Jesus saith unto him, I say not unto thee, Until seven times; but, Until seventy times seven--that is, so long as it shall be needed and sought: you are never to come to the point of refusing forgiveness sincerely asked. (See on Luk 17:3-4).
mat 18:23Therefore--"with reference to this matter."
is the kingdom of heaven likened unto a certain king, which would take account of his servants--or, would scrutinize the accounts of his revenue collectors.
mat 18:24And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents--If Attic talents are here meant, 10,000 of them would amount to above a million and a half sterling; if Jewish talents, to a much larger sum.
mat 18:25But forasmuch as he had not to pay, his lord commanded him to be sold, and his wife and children, and all that he had, and payment to be made--(See Kg2 4:1; Neh 5:8; Lev 25:39).
mat 18:26The servant therefore fell down, and worshipped him--or did humble obeisance to him.
saying, Lord, have patience with me, and I will pay thee all--This was just an acknowledgment of the justice of the claim made against him, and a piteous imploration of mercy.
mat 18:27Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt--Payment being hopeless, the master is first moved with compassion; next, liberates his debtor from prison; and then cancels the debt freely.
mat 18:28But the same servant went out, and found one of his fellow servants--Mark the difference here. The first case is that of master and servant; in this case, both are on a footing of equality. (See Mat 18:33).
which owed him an hundred pence--If Jewish money is intended, this debt was to the other less than one to a million.
and he laid hands on him, and took him by the throat--he seized and throttled him.
saying, Pay me that thou owest--Mark the mercilessness even of the tone.
mat 18:29And his fellow servant fell down at his feet, and besought him, saying, Have patience with me, and I will pay thee all--The same attitude, and the sam words which drew compassion from his master, are here employed towards himself by his fellow servant.
mat 18:30And he would not; but went and cast him into prison, till he should pay the debt, &c.--Jesus here vividly conveys the intolerable injustice and impudence which even the servants saw in this act on the part of one so recently laid under the heaviest obligation to their common master.
mat 18:32Then his lord, after that he had called him, said unto him, O thou wicked servant, &c.--Before bringing down his vengeance upon him, he calmly points out to him how shamefully unreasonable and heartless his conduct was; which would give the punishment inflicted on him a double sting.
mat 18:34And his lord was wroth, and delivered him to the tormentors--more than jailers; denoting the severity of the treatment which he thought such a case demanded.
till he should pay all that was due unto him.
mat 18:35So likewise--in this spirit, or on this principle.
shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.