Charles Ellicott Commentary Jeremiah 3:10

"And yet for all this her treacherous sister Judah hath not returned unto me with her whole heart, but feignedly, saith Jehovah." — Jeremiah 3:10 (ASV)

And yet for all this ... —Judah was so far worse than Israel that there had been a simulated repentance, as in the reformations under Hezekiah and Josiah, but it was not with the whole heart and soul, but “feignedly,” or, more literally, with a lie.