וַיְשַׁנּ֤וֹ אֶת־טַעְמוֹ֙ בְּעֵ֣ינֵיהֶ֔ם וַיִּתְהֹלֵ֖ל בְּיָדָ֑ם ויתו [וַיְתָיו֙] עַל־דַּלְת֣וֹת הַשַּׁ֔עַר וַיּ֥וֹרֶד רִיר֖וֹ אֶל־זְקָנֽוֹ׃
And he changed his demeanour before them, and feigned himself mad in their hands, and scrabbled on the doors of the gate, and let his spittle fall down upon his beard.
Read midrashic interpretation of I Samuel 21:14: and classical rabbinic exegesis.