Charles Ellicott Commentary Matthew 21:15

"But when the chief priests and the scribes saw the wonderful things that he did, and the children that were crying in the temple and saying, Hosanna to the son of David; they were moved with indignation," — Matthew 21:15 (ASV)

The chief priests — As is common in the Gospels, these were the heads of the twenty-four courses of the priesthood, as well as Annas and Caiaphas, who held the title in its higher sense—one as the actual high priest and the other as president of the Sanhedrin (see note on Luke 3:2).

The children — Literally, the boys, as the noun is masculine. Based on the Jewish classification of ages, they would probably have been from seven to fourteen years old, but in a narrative like this, the general phrase does not exclude younger children.