This took place in order that the Prophet's prediction might be fulfilled:

Now this took place so that these words of the prophet might come true,

This took place that it might be fulfilled which was spoken through the prophet, saying,

Now all this was done in order to fulfill what was spoken through the prophet, saying,

This happened in fulfillment of these words in the prophet –

All this was done - The prophecy here quoted is found in Zac 9:9. It was always, by the Jews, applied to the Messiah.
Daughter of Zion - That is, "Jerusalem." "Zion" was one of the hills on which the city of Jerusalem was built. On this stood the city of David and some strong fortresses. The names "daughter and virgin" were given to it often, in accordance with the Oriental figurative manner of expression. See the notes at Isaiah 1:8. Compare Amos 5:2; Psalm 45:13; Psalm 137:8; Isaiah 47:1. It was given to them as an expression of their beauty or comeliness.
Meek - See the notes at Matthew 5:5. The expression here rather denotes "peaceful, not warlike;" not with pomp, and state, and the ensigns of ambition. He came in the manner in which kings were accustomed to ride, but with none of their pride and ambitious feeling.
Sitting upon an ass - He rode on the colt (Mark and Luke). This expression in Matthew is one which is common with all writers. See Genesis 19:29; Judges 12:7.

All this was done - The word all, in this clause, is omitted by some MSS., versions, and fathers.
Which was spoken - The Spirit of God, which predicted those things that concerned the Messiah, took care to have them literally fulfilled:
1. To show the truth of prophecy in general; and,
2. To designate Christ as the person intended by that prophecy.
See the note on Matthew 2:23.

All this was done,.... The disciples were sent to the neighbouring village for the ass and colt, and they brought them, and Christ rode upon them; not because of the distance of the place from Jerusalem, for he was just at it; or because he was weary, or it would be very fatiguing to him to walk thither on foot; for he had been used to travelling, and had gone through most parts of Galilee and Judea; but
that it might be fulfilled which was spoken by the prophet: the Ethiopic version adds, Isaiah; for the former part of the following citation stands in Isaiah 62:11 as the latter does in Zac 9:9. It was usual with the Jews to cite Scripture in this manner, by taking a part from one writer, and another from anther, and joining them together: saying, the following words.

That it might be fulfilled which was spoken by the prophet. See Isaiah 62:11, and Zac 9:9. The prophet here describes him as riding upon one of the humblest of animals, and in the fulfillment we find, (1) that the animal was borrowed; (2) that he rode without a saddle on borrowed garments; (3) that it was a colt on which no man had ever before rode. Only animals hitherto unused were regarded fit for sacred uses. See Numbers 19:2; Deuteronomy 21:3; 1-Samuel 6:7. This is the only instance reported in which the Lord ever rode on any animal.