Praise him, ye heavens of heavens - Referring to the idea that there is one heaven rising above another. See the notes at Psalms 68:33. See 1 Kings 8:27 : “Behold, the heaven and heaven of heavens cannot contain thee.” Compare 2 Chronicles 2:6.
And ye waters that be above the heavens - Genesis 1:7 : “And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament.” The allusion here is to the waters which seem to be above the lower heaven, that is, the air, and which seem to come from some higher region - some higher heaven. See the notes at Psalms 104:3 : “Who layeth the beams of his chambers in the waters.”