When Jesus rode into Jerusalem on what we call Palm Sunday, He fulfilled the prophecy of Zachariah.

""Rejoice greatly, O daughter of Zion! Shout, O daughter of Jerusalem! Behold, your King is coming to you; He is just and having salvation, lowly and riding on a donkey, a colt, the foal of a donkey." - Zechariah 9:9 NKJV

Jesus not only fulfilled Zechariah’s prophesy, He also fulfilled the type and shadow of 1 Kings 1:5-47, when Solomon, the son of David, was revealed to Israel that he was God’s chosen King.

When king David was on his deathbed, his older son Adonijah attempted to take over the throne of Israel, even though Solomon had been chosen by God to be the next king. (1 Chronicles 28:5)

To show all of Israel that Solomon was the chosen king of Israel, David had Solomon ride into Jerusalem on his personal mule that only king David rode on. (1 Kings 1:33-35).

This account of Solomon is a type and shadow of Jesus’ entry into Jerusalem on the donkey. To show all of Israel that Jesus is the chosen king of Israel, Jesus told his disciples to bring Him a donkey that no man had ridden on. (Luke 19:30). When Jesus rode into Jerusalem on the donkey, He displayed that He is the chosen king of Israel.

"Go into the village opposite you, and immediately you will find a donkey tied, and a colt with her. Loose them and bring them to Me." - Matthew 21:2 NKJV (See Zachariah 9:9).

Jesus is called the son of David because according to the lineage of His flesh, He is a descendent of King David. God promised King David that his throne would be established FOREVER. This would be made possible by Messiah. This is why the Jews look for Christ to come from the lineage of King David.

"And thine house and thy kingdom shall be established for ever before thee: thy throne shall be established for ever. According to all these words, and according to all this vision, so did Nathan speak unto David." - 2 Samuel 7:16-17

The angel Gabriel told Mary,

"And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end." - Luke 1:31-33 KJV

Isaiah prophesied,

"For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace. Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the LORD of hosts will perform this." - Isaiah 9:6-7

When the people called Jesus, “Son of David,” they were saying that Jesus is the Messiah, the chosen King of Israel.