עֹצֶ֣ה עֵ֭ינָיו לַחְשֹׁ֣ב תַּהְפֻּכ֑וֹת קֹרֵ֥ץ שְׂ֝פָתָ֗יו כִּלָּ֥ה רָעָֽה׃
He shutteth his eyes, it is to devise froward things; He that biteth his lips bringeth evil to pass.
Read halakhic rulings (Jewish law) on Proverbs 16:30: and classical halakhic sources.