Here "tongue ... in their mouth" represents the things that the tongue enables the mouth to speak. They can be stated in active form. Alternate translation: "none of them will speak deceitful things" or "they will not say deceitful things" (See: [[rc://en/ta/man/jit/figs-activepassive]] and [[rc://en/ta/man/jit/figs-metonymy]])
Yahweh speaks of his provision for the people of Israel as if they are a flock of sheep that grazes and rests in safety. (See: [[rc://en/ta/man/jit/figs-metaphor]])