Matthew 9:27
27As Jesus passed by from there, two blind men followed him, calling out and saying, “Have mercy on us, son of David!”
Blind yet following, shouting for mercy, confessing Jesus as Son of David—Messiah. Need becomes loud prayer.
Cry out. Mercy is asked because it is available. Messianic title on needy lips is already faith speaking.
Davidic confession from the sightless. Providence draws them after the Healer.
“Have mercy” is the right liturgy of the helpless. The title they use is Spirit-taught truth, not mere flattery.