The quote is from (Zech 9:9).

Zechariah 9:9  Rejoice greatly, O Daughter of Zion! Shout, Daughter of Jerusalem! See, your king comes to you, righteous and having salvation, gentle and riding on a donkey, on a colt, the foal of a donkey.

A horse was ridden into war (Job 39:19-25) whereas a donkey was ridden in peace, even by judges, princes, and kings (Judges 10:4; 12:14; 2 Sam 17:23; 19:26). Jesus rode into Jerusalem on a donkey’s colt to symbolize the type of Messiah He was, which was not the kind of messiah the crowd was either expecting or hoping for. They wanted a conquering King; He came as the Prince of Peace (Isaiah 9:6).

Job 39:19-25  “Do you give the horse his strength or clothe his neck with a flowing mane?  Do you make him leap like a locust, striking terror with his proud snorting?  He paws fiercely, rejoicing in his strength, and charges into the fray.  He laughs at fear, afraid of nothing; he does not shy away from the sword.  The quiver rattles against his side, along with the flashing spear and lance.  In frenzied excitement he eats up the ground; he cannot stand still when the trumpet sounds.  At the blast of the trumpet he snorts, ‘Aha!’ He catches the scent of battle from afar, the shout of commanders and the battle cry.

Judges 10:4  He had thirty sons, who rode thirty donkeys. They controlled thirty towns in Gilead, which to this day are called Havvoth Jair.

Judges 12:14  He had forty sons and thirty grandsons, who rode on seventy donkeys. He led Israel for eight years.

2 Samuel 17:23  When Ahithophel saw that his advice had not been followed, he saddled his donkey and set out for his house in his home town. He put his house in order and then hanged himself. So he died and was buried in his father’s tomb.

2 Samuel 19:26  He said, “My lord the king, since I your servant am lame, I said, ‘I will have my donkey saddled and will ride on it, so that I can go with the king.’ But Ziba my servant betrayed me.

Isaiah 9:6  For to us a child is born, to us a son is given, and the government will be on his shoulders. And he will be called Wonderful Counsellor, Mighty God, Everlasting Father, Prince of Peace.

“Fear not” = The New Testament is full of “Fear nots” (Mat 1:20, 10:28,31, 14:27, 17:7, 28:5,10, Mark 5:36, 6:50, Luke 1:13,30, 2:10, 5:10, 8:50, 12:4, 7, 32, John 6:20, Acts 18:9,19, 27:24, 1 Peter 3:14, Rev 1:17, 2:10). God is a God of love and mercy and we should never be afraid of Him (1 John 4:18).

Matthew 1:20  But after he had considered this, an angel of the Lord appeared to him in a dream and said, “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit.

Matthew 10:28  Do not be afraid of those who kill the body but cannot kill the soul. Rather, be afraid of the One who can destroy both soul and body in hell.

Matthew 10:31  So don’t be afraid; you are worth more than many sparrows.

Matthew 14:27  But Jesus immediately said to them: “Take courage! It is I. Don’t be afraid.”

Matthew 17:7  But Jesus came and touched them. “Get up,” he said. “Don’t be afraid.”

Matthew 28:5  The angel said to the women, “Do not be afraid, for I know that you are looking for Jesus, who was crucified.

Matthew 28:10  Then Jesus said to them, “Do not be afraid. Go and tell my brothers to go to Galilee; there they will see me.”

Mark 5:36  Ignoring what they said, Jesus told the synagogue ruler, “Don’t be afraid; just believe.”

1 John 4:18  There is no fear in love. But perfect love drives out fear, because fear has to do with punishment. The one who fears is not made perfect in love.

“Zion” originally indicated the rock escarpment on the ridge between the Kidron and the Tyropeoean Valleys of Jeruslaem. It formed a natural fortress from which the Jebusites defended themselves. It later came to refer to the city of Jerusalem in general in a somewhat poetic manner. “Daughter of Zion” is used to refer to the inhabitants of Jerusalem as a whole.