Charles Ellicott Commentary Psalms 104:13

"He watereth the mountains from his chambers: The earth is filled with the fruit of thy works." — Psalms 104:13 (ASV)

Chambers — i.e., of cloud, as in Psalms 104:3.

Your works. —If we go by the parallelism, this means the “rain,” here called God’s works, as in Psalms 65:9 (see Note), his “river.” Others prefer to see a general reference to the operations of nature which produce fruit.