Judah (Jeremiah 3)
God described Judah's unfaithfulness and His response to that unfaithfulness to the prophet Jeremiah by describing Judah as if it were an unfaithful wife.
Moreover, the Lord said to me in the days of Josiah the king [of Judah],Have you seen what that faithless Israel has done—how she went up on every high hill and under every green tree, and there she was a prostitute? I thought,declares the Lord.After she has done all these things she will return to Me; but she did not return, and her treacherous (faithless) sister Judah saw it. And I saw [that even though Judah knew] that for all the acts of adultery (idolatry) of faithless Israel, I [the Lord] had sent her away and given her a certificate of divorce, yet her treacherous sister Judah was not afraid; but she went and was a prostitute also [following after idols]. Because of the thoughtlessness of Israel’s prostitution [her immorality mattered little to her], she desecrated the land and committed adultery with [idols of] stones and trees. Yet in spite of all this her treacherous sister Judah did not return to Me with her whole heart, but rather in [blatant] deception [she merely pretended obedience to King Josiah’s reforms],
And the Lord said to me,Faithless Israel has proved herself less guilty than treacherous Judah [a land of renegades].— Jeremiah 3:6–3:11 (AMP)
This is similar to how God later described Judah's unfaithfulness (represented by the woman Oholibah) to the prophet Ezekiel.
God then commanded Jeremiah to prophesy to Israel and tell them to return to God and about God's mercy and God's promises to Israel if they return to God.