Albert Barnes Commentary Psalms 24:9

"Lift up your heads, O ye gates; Yea, lift them up, ye everlasting doors: And the King of glory will come in." — Psalms 24:9 (ASV)

Lift up your heads ... — The repetition here is designed to give force and emphasis to what is uttered. The response in Psalm 24:5 is slightly varied from the response in Psalm 24:8; but the same general sentiment is expressed. The design is to announce in a solemn manner that the symbol of the divine presence and majesty was about to be introduced into the place of its permanent abode, and that this was an event worthy to be celebrated; that even the gates of the city should voluntarily open themselves to admit the great and glorious King who was to reign there forever.