Charles Ellicott Commentary Psalms 72:3

"The mountains shall bring peace to the people, And the hills, in righteousness." — Psalms 72:3 (ASV)

The mountains ... —More accurately, literally, Let the mountains and the hills bring forth to the people peace in (or by) righteousness. Most modern commentators preserve this imperative sense, instead of the future, throughout the psalm. The Septuagint uses this sense here and in Psalm 72:17, but elsewhere uses the future.

The verb used here (which properly means “lift up”) is used in Ezekiel 17:8, for “bearing fruit,” and in Isaiah 32:17 peace is described as the natural work or fruit of righteousness. (Compare Psalm 85:10.) For the same prominence given to its hills as the characteristic feature of Palestine, a land which is “not only mountainous, but a heap of mountains,” compare Joel 3:18.