Albert Barnes Commentary Jeremiah 6:21

"Therefore thus saith Jehovah, Behold, I will lay stumbling-blocks before this people; and the fathers and the sons together shall stumble against them; the neighbor and his friend shall perish." — Jeremiah 6:21 (ASV)

“Behold,” I give to “this people” causes of stumbling,
And they shall stumble against them:
Fathers and sons together,
“The neighbor and his friend shall perish.”

This is the natural consequence of their conduct. Their service of Yahweh was a systematic hypocrisy: how then could they walk uprightly with their fellow men? When God lays stumblingblocks in men’s way, it is by the general action of His moral law (James 1:13–14), by which willful sin in one point reacts upon the whole moral nature (James 2:10).