'Mouthpiece' in the Bible

Moreover, he shall speak for you to the people; he will act as a mouthpiece for you, and you will be as God to him [telling him what I say to you].

Therefore, thus says the Lord [to Jeremiah],“If you repent [and give up this mistaken attitude of despair and self-pity], then I will restore you [to a state of inner peace]So that you may stand before Me [as My obedient representative];And if you separate the precious from the worthless [examining yourself and cleansing your heart from unwarranted doubt concerning My faithfulness],You will become My spokesman.Let the people turn to you [and learn to value My values]—But you, you must not turn to them [with regard for their idolatry and wickedness].

I will stand at my guard postAnd station myself on the tower;And I will keep watch to see what He will say to me,And what answer I will give [as His spokesman] when I am reproved.