Likutei Moharan 62:4/ליקוטי מוהר"ן ס״ב:ד׳

14. To perfect faith—i.e., to bring close those who are distant, as explained above—a person must first raise up the sparks of the letters of speech. Once the letters of speech are purified, speech turns itself around and gathers up the sparks of holiness that are among the forces of evil. The evil forces are left without life-force. Then, when the idolaters who are sustained by the evil forces see that they are bereft of life-force, they cast off their beliefs—the aspect of “At that time a man will cast away his idols of silver and his idols of gold” (Isaiah 2:20)—and adhere to the faith of the Jews.

2This is the aspect of “For then I will turn [the speech of] the nations into pure speech.” “Pure speech” is speech that has been purified [and removed] from their midst. It turns itself to the nations in order to gather up the remaining holy sparks from them. Thus is fulfilled “that they may all call out in God’s Name”—they all adhere to the faith of the Jews.