Psalms 48:5

"They saw it, and so they marvelled" [Psalm 48:4]. After their marvelling at the miracles and glory of Christ, what followed? "They were troubled, they were moved" [Psalm 48:5], "trembling took hold upon them." Whence took trembling hold upon them, but from the consciousness of sins? Let them run then, king after a king; kings, let them acknowledge the King. Therefore says He elsewhere, "Yet have I been set by Him a King upon His holy hill of Sion."...A King then was heard of, set up in Sion, to Him were delivered possessions even to the uttermost parts of the earth. Kings behooved to fear lest they should lose the kingdom, lest the kingdom be taken from them. As wretched Herod feared, and for the Child slew the children. [Matthew 2:16] But fearing to lose his kingdom, he deserved not to know the King. Would that he too had adored the King with the Magi: not by ill-seeking the kingdom, slain the Innocents, and perished guilty. For as concerning him, he destroyed the Innocents: but as for Christ, even a Child, the children dying for Him did He crown. Therefore behooved kings to fear when it was said, "Yet have I been set a King by Him upon His holy hill of Sion," and inheritance to the uttermost parts of the earth shall He give Him, who set Him up King....Thence also this is said to them, "Understand now therefore, O you kings; be instructed, you judges of the earth. Serve the Lord with fear, and rejoice unto Him with trembling." And what did they? "There pains as of a woman in travail." What are the pains "as of a woman in travail," but the pangs of a penitent? See the same conception of pain and travail: "Of Your fear" (says Isaiah) "we have conceived, we have travailed of the Spirit of salvation." [Isaiah 26:17-18] So then the kings conceived from the fear of Christ, that by travailing they brought forth salvation by believing on Him whom they had feared. "There pains as of a woman in travail:" when of travail you hear, expect a birth. The old man travails, but the new man is born.