וַיַּ֤עַן מֹשֶׁה֙ וַיֹּ֔אמֶר וְהֵן֙ לֹֽא־יַאֲמִ֣ינוּ לִ֔י וְלֹ֥א יִשְׁמְע֖וּ בְּקֹלִ֑י כִּ֣י יֹֽאמְר֔וּ לֹֽא־נִרְאָ֥ה אֵלֶ֖יךָ יְהוָֽה׃
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.’
Read kabbalistic (mystical) interpretation of Exodus 4:1: and classical mystical sources.