Zechariah 9:9-10 is the key OT prophecy behind the entry — the messiah comes humble on a donkey bringing salvation through service, not military conquest. The donkey vs. war horse contrast is central.

Zechariah 9:9: "Rejoice greatly, O daughter of Zion... your king is coming to you; he is just and endowed with salvation, humble and mounted on a donkey." This was well-known messianic prophecy — Jews at the time knew exactly what Jesus was claiming. The prophecy emphasizes the king is humble, bringing salvation, riding a beast of burden — matching Mark 10:45 ("Son of Man came to serve and give his life a ransom for many"). Zechariah 9:10 adds God will "cut off the chariot" and "the horse from Jerusalem" — salvation comes through humble service, not warfare. The irony was prepared in OT prophecy, not just in Jesus' actions.