Charles Spurgeon Commentary Jeremiah 3:7

"And I said after she had done all these things, She will return unto me; but she returned not: and her treacherous sister Judah saw it." — Jeremiah 3:7 (ASV)

And I said after she had done all these things, Turn thou unto me.

But she returned not. And her treacherous sister Judah saw it.

That made Judah's sin even worse than that of Israel; she saw this great iniquity in another, and yet went and committed it herself.