Jeremiah 4:1 & 2
"'If you, Israel, will return, then return to me,' declares the Lord. 'If you put your detestable idols out of my sight and no longer go astray, and if in a truthful, just and righteous way you swear "As surely as the Lord lives," then the nations will invoke blessings by him and in him they will boast.'" NIV translation
In chapter three, the prophet began to remind the people of what had happened to the northern kingdom. He shared the fact that God had called them to repent but they had refused and dug in their heels like a stubborn calf. The phrase "the nations will invoke blessings by him" refers to the fact that God had promised Abraham that God would make him a blessing (see Genesis 12). This is a reminder that Israel was to be a bright shining light in the dark pagan world.