Zech 9:9, Ps 118:26, Jn 1:49, Jn 18:37
The Old Testament prophesied that Christ would enter Jerusalem on the colt of a donkey as King of Israel. (Zech 9:9)
Zech 9:9 Rejoice greatly, O daughter of Zion; shout, O daughter of Jerusalem: behold, thy King cometh unto thee: he is just, and having salvation; lowly, and riding upon an ass, and upon a colt the foal of an ass.
Also, the Old Testament said that Christ would come in the name of the Lord. (Ps 118:26)
Ps 118:26 Blessed be he that cometh in the name of the Lord: we have blessed you out of the house of the Lord.
Jesus is the Christ who came to this earth as the King of Israel. (Jn 1:49, Jn 12:12-16, Jn 18:37)
Jn 1:49 Nathanael answered and saith unto him, Rabbi, thou art the Son of God; thou art the King of Israel.
Jn 12:12 On the next day much people that were come to the feast, when they heard that Jesus was coming to Jerusalem, 13 Took branches of palm trees, and went forth to meet him, and cried, Hosanna: Blessed is the King of Israel that cometh in the name of the Lord. 14 And Jesus, when he had found a young ass, sat thereon; as it is written, 15 Fear not, daughter of Sion: behold, thy King cometh, sitting on an ass's colt. 16 These things understood not his disciples at the first: but when Jesus was glorified, then remembered they that these things were written of him, and that they had done these things unto him.
Jn 18:37 Pilate therefore said unto him, Art thou a king then? Jesus answered, Thou sayest that I am a king. To this end was I born, and for this cause came I into the world, that I should bear witness unto the truth. Every one that is of the truth heareth my voice.