בְּעֶבְרַ֛ת יְהוָ֥ה צְבָא֖וֹת נֶעְתַּ֣ם אָ֑רֶץ וַיְהִ֤י הָעָם֙ כְּמַאֲכֹ֣לֶת אֵ֔שׁ אִ֥ישׁ אֶל־אָחִ֖יו לֹ֥א יַחְמֹֽלוּ׃
Through the wrath of the LORD of hosts is the land burnt up; the people also are as the fuel of fire; No man spareth his brother.
Read halakhic rulings (Jewish law) on Isaiah 9:18: and classical halakhic sources.