The letter "tav" (תיו - tav/taw/tau), marking the righteous and the wicked in Ezekiel 9:4, is discussed in this sugya, see Ezekiel.9.3-6, bolding and italics mine:
Divine Symbols and Historical Shifts: The…
The letter "tav" (תיו - tav/taw/tau), marking the righteous and the wicked in Ezekiel 9:4, is discussed in this sugya, see Ezekiel.9.3-6, bolding and italics mine: