Jeremiah 3:23
Truly in vain is salvation hoped for from the hills, and from the multitude of mountains: truly in the LORD our God is the salvation of Israel. Truly in vain is salvation hoped for from the hills, and from the multitude of mountains: truly in the LORD our God is the salvation of Israel.
The hills and the multitude of mountains are the idolatrous high places where Israel sought help. Those shrines had been cleansed from the land in Josiah's reformation, while the hearts of the multitude had not been transformed. Salvation hoped for from those hills and mountains is vain. Israel's salvation is truly only in the Lord God, with no other source of salvation apart from Him.
The verse is spoken as the people's confession in returning to God: they admit their own and their fathers' sins and disobedience and acknowledge their hope is in Him for healing and restoration. Only as the nation proves loyal to Jehovah can it hope for divine favor and prosperity. The verse was meant to arouse the nation to its danger after backsliding had choked the springing seeds of truth like thorns, warning that another such backsliding would be fatal. No one can redeem himself or escape the enemy's power by his own means; salvation comes through accepting Christ as personal Saviour.