Commentators explain that Ruth's words are not just an emotional promise but a formal, solemn oath. By invoking "Jehovah," the God of Israel, she is officially transferring her allegiance from the gods of Moab. The phrase "the Lord do so to me, and more also" was a standard formula for an unbreakable vow, demonstrating the absolute finality of her decision and convincing Naomi to cease her protests.