Albert Barnes Commentary Jeremiah 5:3

"O Jehovah, do not thine eyes look upon truth? thou hast stricken them, but they were not grieved; thou hast consumed them, but they have refused to receive correction: they have made their faces harder than a rock; they have refused to return." — Jeremiah 5:3 (ASV)

Upon the truth - God looks to the “faith,” the upright purpose of the heart, and without it the nominal allegiance of an oath is an abomination.