Charles Ellicott Commentary Jeremiah 3:23

"Truly in vain is [the help that is looked for] from the hills, the tumult on the mountains: truly in Jehovah our God is the salvation of Israel." — Jeremiah 3:23 (ASV)

Truly in vain ... —The italics indicate the difficulty of the verse and represent an attempt to resolve it. According to the possible meanings of the word translated “multitude,” we can understand it as in vain (literally, as a lie) from the hills is the revelry (Amos 5:23), or the wealth, or the multitude, of the mountains. The first option gives the best meaning and expresses the confession of the repentant Israelites that their wild ritual on the high places had brought them loss and not gain.