Musar for Shabbat 109:5

The letter ת possesses another peculiarity, namely that it signifies death, written in blood, as we know from the statement of Rabbi Acha bar Chanina in Shabbat 55a. He tells us that G–d had never issued a favorable decree and reversed Himself except in a single instance, viz. the situation referred to in Ezekiel 9,4 when G–d told the angel Gabriel: "Pass in the midst of the city, in the midst of Jerusalem, and mark a sign on the foreheads of the men who sigh and groan for all the abominations that are done within it." G–d had instructed Gabriel to place on the foreheads of the righteous the letter ת in ink so that the Divinely appointed forces of destruction should not touch those people. The foreheads of the wicked people, however, were to be marked with the same letter written in blood, so that they would fall victim to the forces of destruction. The ministering angels challenged G–d on this decision, wanting to know in what way the former were better than the latter, seeing that they had failed to perform the commandment of admonishing their fellow-Jews. G–d answered these angels that He was well aware that even if the righteous people had admonished their compatriots it would have been to no avail. To this the angels replied that the fact that G–d was aware that such admonitions would have proved futile did not absolve the righteous from at least having tried, seeing that they had no way of knowing whether their attempts to admonish the people would prove successful. As a result of this, we read in verse 5 of the same chapter: "Then He said to these in my hearing (the prophet's) 'Follow him through the city and strike. Let your eyes neither spare nor show mercy. Old man, young man and maiden, children and women, massacre to utter destruction. But any man on whom is the sign do not approach. And begin from My Sanctuary' i.e, Mikdashay so they began with the old men who were in front of the House." Rabbi Yosef reads the word Mikdashay as Me-kudashay, i.e. "My holy ones," the people who observed all the commandments of the Torah from the letter Aleph, to the letter Tav. So far the quotation from the Talmud in Shabbat 55. A few lines further on the Talmud questions why the sign chosen for these markings had been the letter ת, and answers that this letter is the first letter of the word Tichyeh, i.e. "you will live," as well as the first letter of the word Tamut, i.e. "you will die." Shmuel said that the reason is that at that point the merit of the patriarchs had been exhausted and it no longer could be called upon to protect their descendants from G–ds anger. Rabbi Yochanan, however, feels that the letter ת symbolised that these people could be granted grace only through the merit of the patriarchs. Rabbi Shimon ben Lakish, also on that folio, says that that letter is the final letter in G–d's "seal," seeing that Rabbi Chanina taught that the "seal" of G–d is אמת, "Truth." At any rate, we know that the combination of the letters מ-ת spelled death, since there was a מגפה, a deadly plague, which killed twenty-four thousand Israelites at that time. The letter ת discussed in the Talmud is also known to have been written in blood on the foreheads of the wicked.