John Chrysostom

It was not at the command of the governor that they did this, but in order to gratify the Jews. For neither were they commanded by him to go to the garden in the night, but the Jews gave them money to go. He bore however all these insults silently. Yet do thou, when thou hearest of them, keep stedfastly in thy mind the King of the whole earth, and Lord of Angels bearing all these contumelies in silence, and imitate His example.

Catena Aurea by Aquinas ↗

Theophylact of Ohrid

But the soldiers do everything to please the Jews. They had heard Pilate say, "I will release the King of the Jews"; therefore they mock Him as a king. For it was not by Pilate's order that they did this, nor did those who went against Jesus at night do so with the governor's knowledge, but to please the Jews, for the sake of money.

Commentary on John ↗

Thomas Aquinas

2377 Thirdly, they mock him the way they address him: they came up to him, saying, Hail, King of the Jews! It was the custom then, as it is now, for subjects to salute their king when they came into his presence: "And when Hushai the Archite, David's friend, came to Absalom, Hushai said to Absalom, 'Long live the king! Long live the king!'" (2 Sam 16:16). As for the mystical interpretation, those greet Christ mockingly who profess him with words "but deny him with their deeds" (Titus 1:16). …

Commentary on John ↗

Bonaventure

Then the mockery in the salutation: whence he says: And they came to him and said: Hail, King of the Jews, and this indeed as a reproach: Lamentations three: "He shall be filled with reproaches." — Not only in word, but in reverence, because in place of reverence they gave slaps: whence he says: And they gave him slaps: Lamentations three: "He shall give his cheek to him that strikes him"; and Isaiah fifty: "I have given my body to the strikers and my cheeks to those who plucked them."

Commentary on John, Chapter 19 ↗