Don't judge him by how he looks
(Slang) By extension: He is not as simple a person as he appears to you.
(Modern Hebrew)
Translation
Expression (Hebrew)
אַל תִּרְאֶה אוֹתוֹ כָּכָה
Definition (Hebrew)
(סְלָאנֶג) בְּהַשְׁאָלָה: הוּא אֵינוֹ אָדָם פָּשׁוּט כְּמוֹ שֶׁהוּא נִרְאֶה לְךָ.
(הָעִבְרִית הַחֲדָשָׁה)