Matthew
27 And as Jesus passed on from there, two blind men followed him, crying aloud, “Have mercy on us, Son of David.”
28 When he entered the house, the blind men came to him, and Jesus said to them, “Do you believe that I am able to do this?” They said to him, “Yes, Lord.”
29 Then he touched their eyes, saying, “According to your faith be it done to you.”
30 And their eyes were opened. And Jesus sternly warned them, “See that no one knows about it.”
31 But they went away and spread his fame through all that district.
Son of David
This name firmly places Jesus in the line of the kings of Judah. Calling Him the son of David is confessing that He is God's chosen King.
This phrase isn't very common in the gospels. These blind men, the blind men in another account by Matthew (20:29–34), and a Canaanite woman (Matthew 15:21–28) are the only ones to make this confession public when coming to Him for healing. And the crowds shouted "Hosanna to the Son of David!" when Jesus came to Jerusalem (Matthew 21:1–11), adding "Son of David" to the words of Psalm 118:26.
But Jesus gets the last word on the topic (Matthew 22:41–46) when He asks a question no one can answer:
Matthew 22:45
If then David calls him Lord, how is he his son?
I am able to do this
Here we note that Matthew has not specifically recorded their request; they only said "have mercy on us," and He only asked if they believed He could do "this." While it's clear enough that their request is to have sight, Matthew seems intentionally not to specify that request in his writing. By doing this, Matthew builds our anticipation through to the next verse.
According to your faith be it done
Here, too, we note Matthew does not specify what "it" is that will be done. We must wait until the next verse to see what it was they believed could happen!
It is worth observing Matthew has been making someone's healing proportionate to their faith for a while now in his gospel. We must believe in the power of God if we want it to work in our lives!
Matthew 8:13
And to the centurion Jesus said, “Go; let it be done for you as you have believed.” And the servant was healed at that very moment.
Matthew 9:22
Jesus turned, and seeing her he said, “Take heart, daughter; your faith has made you well.” And instantly the woman was made well.
sternly warned them
As Mark 1:45 told us, the purpose of this charge is to keep the crowds from becoming overwhelming. Jesus wants to teach where the people can get to Him easily.
See
The first thing they "see" in Matthew's account is a commandment from Jesus.
Likewise, we today come to Him for forgiveness, and we must follow His commandments from then on.
1 Peter 4:1–3
Since therefore Christ suffered in the flesh, arm yourselves with the same way of thinking, for whoever has suffered in the flesh has ceased from sin, so as to live for the rest of the time in the flesh no longer for human passions but for the will of God. For the time that is past suffices for doing what the Gentiles want to do....
spread his fame through all that district
It is a pattern in the gospels that people have an unfortunate tendency to spread the news of Jesus's miracles even when He charges them to say nothing about it. In the episode right before this one, for example, Jesus charges the resurrected girl's parents to tell no one what happened (Luke 8:56), but "the report of this went through all that district" (Matthew 9:26) anyway. Some accounts tell us people outright disobeyed Jesus and immediately began to tell it; others leave room for the possibility that they obeyed Him, but people still found out simply by observation. Rather than focusing on some peoples' failure to heed instruction, we ought to see the larger meaning of it: the works of God cannot remain hidden!
Luke 19:36–40
And as he rode along, they spread their cloaks on the road. As he was drawing near—already on the way down the Mount of Olives—the whole multitude of his disciples began to rejoice and praise God with a loud voice for all the mighty works that they had seen, saying, “Blessed is the King who comes in the name of the Lord! Peace in heaven and glory in the highest!” And some of the Pharisees in the crowd said to him, “Teacher, rebuke your disciples.” He answered, “I tell you, if these were silent, the very stones would cry out.”