מְ֭קַלֵּל אָבִ֣יו וְאִמּ֑וֹ יִֽדְעַ֥ךְ נֵ֝ר֗וֹ באישון [בֶּאֱשׁ֥וּן] חֹֽשֶׁךְ׃
Whoso curseth his father or his mother, his lamp shall be put out in the blackest darkness.
Read halakhic rulings (Jewish law) on Proverbs 20:20: and classical halakhic sources.