כִּ֤י בָאֵשׁ֙ יְהוָ֣ה נִשְׁפָּ֔ט וּבְחַרְבּ֖וֹ אֶת־כָּל־בָּשָׂ֑ר וְרַבּ֖וּ חַֽלְלֵ֥י יְהוָֽה׃
For by fire will the LORD contend, And by His sword with all flesh; And the slain of the LORD shall be many.
Read kabbalistic (mystical) interpretation of Isaiah 66:16: and classical mystical sources.