from Ezekiel 9:4
https://www.sefaria.org/Ezekiel.9.4?lang=en&with=all&lang2=en
and put a mark on the foreheads of the persons who moan and groan because of all the abominations that are committed in it
והתוית תו על-מצחות האנשים, הנאנחים והנאנקים, על כל-התועבות, הנעשות בתוכה
Psalm 14:3
https://www.sefaria.org/Psalms.14.3?lang=en&with=all&lang2=en
All have turned bad, altogether foul; there is none who does good, not even one.
הכל סר, יחדו נאלחו: אין עשה-טוב--אין, גם-אחד
A mark on those turned bad
סרתו
Classical Hebrew numbering (as used for page numbers/calenders)
סרתו counts (ס + 200=ר + 400=ת + 6=ו=s60) = 666
https://www.sefaria.org/Ezekiel.9.4?lang=en&with=all&lang2=en
and put a mark on the foreheads of the persons who moan and groan because of all the abominations that are committed in it
והתוית תו על-מצחות האנשים, הנאנחים והנאנקים, על כל-התועבות, הנעשות בתוכה
Psalm 14:3
https://www.sefaria.org/Psalms.14.3?lang=en&with=all&lang2=en
All have turned bad, altogether foul; there is none who does good, not even one.
הכל סר, יחדו נאלחו: אין עשה-טוב--אין, גם-אחד
A mark on those turned bad
סרתו
Classical Hebrew numbering (as used for page numbers/calenders)
סרתו counts (ס + 200=ר + 400=ת + 6=ו=s60) = 666