וְשָׁלַחְתִּ֤י אֶת־יָדִי֙ וְהִכֵּיתִ֣י אֶת־מִצְרַ֔יִם בְּכֹל֙ נִפְלְאֹתַ֔י אֲשֶׁ֥ר אֶֽעֱשֶׂ֖ה בְּקִרְבּ֑וֹ וְאַחֲרֵי־כֵ֖ן יְשַׁלַּ֥ח אֶתְכֶֽם׃
And I will put forth My hand, and smite Egypt with all My wonders which I will do in the midst thereof. And after that he will let you go.
Read halakhic rulings (Jewish law) on Exodus 3:20: and classical halakhic sources.