כִּֽי־קָר֥וֹב יוֹם־יְהוָ֖ה עַל־כָּל־הַגּוֹיִ֑ם כַּאֲשֶׁ֤ר עָשִׂ֙יתָ֙ יֵעָ֣שֶׂה לָּ֔ךְ גְּמֻלְךָ֖ יָשׁ֥וּב בְּרֹאשֶֽׁךָ׃
For the day of the LORD is near upon all the nations; As thou hast done, it shall be done unto thee; Thy dealing shall return upon thine own head. .
Read halakhic rulings (Jewish law) on Obadiah 1:15: and classical halakhic sources.