Now therefore go, and I will be with thy mouth, and teach thee what thou shalt say. I will be with thy mouth - The Chaldee translates, My Word, meimeri, shall be with thy mouth. And Jonathan ben Uzziel paraphrases, I and my Word will be with the speech of thy mouth. See Clarke on Genesis 15:1 (note), and Leviticus 25:10 (note).
Related Commentaries of Exodus 4:12
Exodus 4:12
12 Now therefore go, and I will be with thy mouth, and teach thee what thou shalt say.