Don't confuse him with facts
Figuratively: There is no point in trying to persuade him or presenting him with facts because he is firmly attached to his position.
(Modern Hebrew)
Translation
Expression (Hebrew)
אַל תְּבַלְבֵּל אוֹתוֹ עִם עוּבְדוֹת
Definition (Hebrew)
בְּהַשְׁאָלָה: אֵין טַעַם לְשַׁכְנֵעַ אוֹתוֹ וּלְהָבִיא מבפניו עֻבְדּוֹת כִּי הוּא דֶּבֶק בעמדתו.
(הָעִבְרִית הַחֲדָשָׁה)