“This took place

To fulfill

What had been spoken

Through the prophet.

Saying.

‘Tell the daughter of Zion!

Look!

Your king is coming

To you,

Humble,

Mounted on a donkey,

And on a colt,

The foal of a donkey.’”

Τοῦτο δὲ γέγονεν ἵνα πληρωθῇ τὸ ῥηθὲν διὰ τοῦ προφήτου λέγοντος

Εἴπατε τῇ θυγατρὶ Σιών Ἰδοὺ ὁ Βασιλεύς σου ἔρχεταί σοι πραῢς καὶ ἐπιβεβηκὼς ἐπὶ ὄνον καὶ ἐπὶ πῶλον υἱὸν ὑποζυγίου.

This is unique to Matthew.  Jesus said that this activity took place (Τοῦτο δὲ γέγονεν) to fulfill what had been spoken through the prophet (ἵνα πληρωθῇ τὸ ῥηθὲν διὰ τοῦ προφήτου λέγοντος).  Although not named, this prophet was Zechariah, chapter 9:9, one of the 12 minor prophets that lived in the 6^th century BCE under Persian rule.  This prophet had said to tell the daughter of Zion (Εἴπατε τῇ θυγατρὶ Σιών) to look for their king coming to them (Ἰδοὺ ὁ Βασιλεύς σου ἔρχεταί σοι).  He would be humble, mild, or gentle (πραῢς), but mounted on a donkey (καὶ ἐπιβεβηκὼς ἐπὶ ὄνον) and a colt, that was the foal or son of a donkey (καὶ ἐπὶ πῶλον υἱὸν ὑποζυγίου).  This was an actual misreading of the prophet, since Zechariah had spoken of a young colt donkey, who had been the foal of a donkey, not two separate animals.  Matthew used this passage to show how Jesus was the expected Israelite king.  He was to be the prince of peace.  Originally, Yahweh wanted Zion or Jerusalem to shout and rejoice, because their new king was coming.  He would be triumphant, victorious, and humble at the same time, but riding on a young donkey colt.  Matthew’s intention was clear.  Jesus was the expected messiah king.