Albert Barnes Commentary Psalms 148:9

"Mountains and all hills; Fruitful trees and all cedars;" — Psalms 148:9 (ASV)

Mountains, and all hills - As they are among the loftiest objects of earth, raising their heads highest toward the heavens.

Fruitful trees, and all cedars - Fruitful trees, not as distinguished from those that are barren, but as distinguished from forest trees, which by nature do not bear fruit. Of the latter, the cedar was the most prominent, and, therefore, is made the representative of all of them.