Why does Ephraim say that the Lord has disciplined him “like an untrained calf”?

The offer of hope and comfort to Israel in Jeremiah 31:16–17 is followed by a passage of repentance in Jeremiah 31:18–20. The Lord says he has heard Ephraim grieving. Ephraim here personifies his descendants and refers to the northern tribes who were taken into exile. They acknowledge what the Lord was doing when he sent them into exile: You have disciplined me, and I was disciplined, like an untrained calf. They acknowledge and accept the Assyrian invasion and deportation as discipline from the Lord for the purpose of restoring their relationship with him. They describe their behaviour as that of an untrained calf which is in stark contrast to how the Lord describes them in Hosea 10:11 as a trained calf. Hosea is referring to the beginnings of Israel’s relationship with the Lord, when they willingly accepted the covenant. But that soon changed and Israel very soon rejected the covenant (see Jeremiah 2:20; Jeremiah 5:5;Hosea 4:16). Throughout Jeremiah the people of Israel, both north and south, are described as a nation that refused correction from the Lord (Jeremiah 2:30;Jeremiah 5:3;Jeremiah 7:28;Jeremiah 17:23; Jeremiah 32:33). But now some among the northern tribes have accepted that correction and they cry out to the Lord, Bring me back that I may be restored. They are calling on the Lord to bring them back to the land and with the words, for you are the Lord my God, these exiles submit themselves once again to the covenant¹. The message to the people of Judah is that the Lord has heard Ephraim grieving. He has heard and accepted their repentance, which would give great assurance to those in Judah who are about to face exile in Babylon, or when they read it as exiles². Even though judgment has come it is not the end for those who will turn to the Lord.