We have here the same account of Christ's riding in some sort of triumph (such as it was) into Jerusalem which we had before in Matthew and Mark; let us therefore here only observe,
I. Jesus Christ was forward and willing to suffer and die for us. He went forward, bound in the spirit, to Jerusalem, knowing very well the things that should befall him there, and yet he went before, ascending up to Jerusalem, Luk 19:28. He was the foremost of the company, as if he longed to be upon the spot, longed to engage, to take the field, and to enter upon action. Was he so forward to suffer and die for us, and shall we draw back from any service we are capable of doing for him?
II. It was no ways inconsistent either with Christ's humility or with his present state of humiliation to make a public entry into Jerusalem a little before he died. Thus he made himself to be the more taken notice of, that the ignominy of his death might appear the greater.
III. Christ is entitled to a dominion over all the creatures, and may use them when and as he pleases. No man has a property in his estate against Christ, but that his title is prior and superior. Christ sent to fetch an ass and her colt from their owner's and master's crib, when he had occasion for their service, and might do so, for all the beasts of the forest are his, and the tame beasts too.
IV. Christ has all men's hearts both under his eye and in his hand. He could influence those to whom the ass and the colt belonged to consent to their taking them away, as soon as they were told that the Lord had occasion for them.
V. Those that go on Christ's errands are sure to speed (Luk 19:32): They that were sent found what he told them they should find, and the owners willing to part with them. It is a comfort to Christ's messengers that they shall bring what they are sent for, if indeed the Lord has occasion for it.
VI. The disciples of Christ, who fetch that for him from others which he has occasion for, and which they have not, should not think that enough, but, whatever they have themselves wherewith he may be served and honoured, they should be ready to serve him with it. Many can be willing to attend Christ at other people's expense who care not to be at any charge upon him themselves; but those disciples not only fetched the ass's colt for him, but cast their own garments upon the colt, and were willing that they should be used for his trappings.
VII. Christ's triumphs are the matter of his disciples' praises. When Christ came nigh to Jerusalem, God put it of a sudden into the hearts of the whole multitude of the disciples, not of the twelve only, but abundance more, that were disciples at large, to rejoice and praise God (Luk 19:37), and the spreading of their clothes in the way (Luk 19:36) was a common expression of joy, as at the feast of tabernacles. Observe, 1. What was the matter or occasion of their joy and praise. They praised God for all the mighty works they had seen, all the miracles Christ had wrought, especially the raising of Lazarus, which is particularly mentioned, Joh 12:17, Joh 12:18. That brought others to mind, for fresh miracles and mercies should revive the remembrance of the former. 2. How they expressed their joy and praise (Luk 19:38): Blessed be the king that cometh in the name of the Lord. Christ is the king; he comes in the name of the Lord, clothed with a divine authority, commissioned from heaven to give law and treat of peace. Blessed be he. Let us praise him, let God prosper him. He is blessed for ever, and we will speak well of him. Peace in heaven. Let the God of heaven send peace and success to his undertaking, and then there will be glory in the highest. It will redound to the glory of the most high God; and the angels, the glorious inhabitants of the upper world, will give him the glory of it. Compare this song of the saints on earth with that of the angels, Luk 2:14. They both agree to give glory to God in the highest. There the praises of both centre; the angels say, On earth peace, rejoicing in the benefit which men on earth have by Christ; the saints say, Peace in heaven, rejoicing in the benefit which the angels have by Christ. Such is the communion we have with the holy angels that, as they rejoice in the peace on earth, so we rejoice in the peace in heaven, the peace God makes in his high places (Job 25:2), and both in Christ, who hath reconciled all things to himself, whether things on earth or things in heaven.
VIII. Christ's triumph's, and his disciples' joyful praises of them, are the vexation of proud Pharisees, that are enemies to him and his kingdom. There were some Pharisees among the multitude who were so far from joining with them that they were enraged at them, and, Christ being a famous example of humility, they thought that he would not admit such acclamations as these, and therefore expected that he should rebuke his disciples, Luk 19:39. But it is the honour of Christ that, as he despises the contempt of the proud, so he accepts the praises of the humble.
IX. Whether men praise Christ or no he will, and shall, and must be praised (Luk 19:40): If these should hold their peace, and not speak the praises of the Messiah's kingdom, the stones would immediately cry out, rather than that Christ should not be praised. This was, in effect, literally fulfilled, when, upon men's reviling Christ upon the cross, instead of praising him, and his own disciples' sinking into a profound silence, the earth did quake and the rocks rent. Pharisees would silence the praises of Christ, but they cannot gain their point; for as God can out of stones raise up children unto Abraham, so he can out of the mouths of those children perfect praise.

See this triumphal entry into Jerusalem explained at large on Mat 21:1-11 (note), and Mar 11:1-10 (note).

And if any man ask you, why do ye loose him?.... As our Lord, being God omniscient, knew this question would be asked by the owners, and therefore prepares his disciples with an answer to it:

thus shall ye say unto him, because the Lord hath need of him. The Syriac and Persic versions read "our Lord", yours, and ours; probably the owners of the colt might be such as knew the Lord Jesus Christ, and by this way of speaking of him, knew, at once, who was meant, and so made no scruple of sending him, as Christ told them they would not, and so they found it; See Gill on Mat 21: 3 and See Gill on Mar 9:3

whereon, &c.--(See on Joh 19:41).