To be confused/ grow foolish
He acted without thinking. He made a mistake. He behaved with a stupidity that is not characteristic of his intellectual ability.
("Therefore, behold, I will continue to do a marvelous work among this people: a marvelous work, and a marvelous work; and the wisdom of their wise men shall perish, and the understanding of their prudent men shall be hid" - Isaiah 29:11)
Translation
Expression (Hebrew)
הִסְתַּתְּרָה בִּינָתוֹ, נִסְתַּתְּרָה בִּינָתוֹ
Definition (Hebrew)
נָהַג לְלֹא מַחְשָׁבָה. טָעָה. הִתְנַהֵג בְּטִפְּשׁוּת שֶׁאֵינָהּ אָפְיָנִית לִיכָלְתּוֹ הַשִּׂכְלִית.
("לָכֵן הִנְנִי יוֹסִף לְהַפְלִיא אֶת הָעָם הַזֶּה הַפְלֵא וָפֶלֶא וְאָבְדָה חָכְמַת חֲכָמָיו וּבִינַת נְבֹנָיו תִּסְתַּתָּר"- יְשַׁעְיָהוּ כט יָד)