They will not hearken to my voice — That is, they would not take his bare word, unless he shewed them some sign. He remembered how they had once rejected him, and feared it would be so again.
Related Commentaries of Exodus 4:1
Exodus 4:1
1 And Moses answered and said, But, behold, they will not believe me, nor hearken unto my voice: for they will say, The LORD hath not appeared unto thee.