That they may believe that the LORD God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath appeared unto thee. That they may believe - This is an example of what is called an imperfect or unfinished speech, several of which occur in the sacred writings. It may be thus supplied: Do this before them, that they may believe that the Lord hath appeared unto thee.
Related Commentaries of Exodus 4:5
Exodus 4:5
5 That they may believe that the LORD God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath appeared unto thee.