What does Matthew 21:15 mean?
Some children in the temple noticed Jesus chasing moneychangers and corrupt businessmen from the temple marketplace (Matthew 21:12–13). They saw Him heal blind and lame people who came to Him for help (Matthew 21:14). Now they begin echoing the shouts from the previous day (Matthew 21:9), when Jesus entered the city: "Hosanna to the Son of David!"Why were the chief priests and scribes so indignant about this? They understood that "Son of David" was a reference to the long-promised Messiah of Israel. Calling Jesus the Promised One would have angered those religious leaders. Also, the passage from which the word "Hosanna" was taken was meant to be directed to God alone. Since these critics did not believe in Christ, that would be especially offensive to them. They wanted Jesus to stop the children from praising Him in this way.
The children, though, had made a connection that the priests and scribes refused to acknowledge. Whether by accident or insight, they praised Jesus as the Messiah because they saw His displays of power and authority. Jesus would not correct them.