The Gemara teaches that the seal of the Holy One is emet (truth), and that Torah and truth are bound together — the Torah's completeness is expressed through the fact that it contains no falsehood or half-measure.
וְהַיְינוּ דִּכְתִיב: ״זָקֵן בָּחוּר וּבְתוּלָה טַף וְנָשִׁים תַּהַרְגוּ לְמַשְׁחִית וְעַל כׇּל אִישׁ אֲשֶׁר עָלָיו הַתָּו אַל תִּגַּשׁוּ וּמִמִּקְדָּשִׁי תָּחֵלּוּ״. וּכְתִיב: ״וַיָּחֵלּוּ בָּאֲנָשִׁים הַזְּקֵנִים אֲשֶׁר לִפְנֵי הַבָּיִת״. תָּנֵי רַב יוֹסֵף: אַל תִּקְרֵי ״מִקְדָּשִׁי״ אֶלָּא ״מְקוּדָּשַׁי״ — אֵלּוּ בְּנֵי אָדָם שֶׁקִּיְּמוּ אֶת הַתּוֹרָה כֻּלָּהּ מֵאָלֶף וְעַד תָּיו. וּמִיָּד: ״וְהִנֵּה שִׁשָּׁה אֲנָשִׁים בָּאִים מִדֶּרֶךְ שַׁעַר הָעֶלְיוֹן אֲשֶׁר מׇפְנֶה צָפוֹנָה וְאִישׁ כְּלִי מַפָּצוֹ בְּיָדוֹ וְאִישׁ אֶחָד בְּתוֹכָם לָבֻשׁ הַבַּדִּים וְקֶסֶת הַסּוֹפֵר בְּמׇתְנָיו וַיָּבֹאוּ וַיַּעַמְדוּ אֵצֶל מִזְבַּח הַנְּחוֹשֶׁת״. וְרֵישׁ לָקִישׁ אָמַר: ״תָּיו״ — סוֹף חוֹתָמוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא, דְּאָמַר רַבִּי חֲנִינָא: חוֹתָמוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא ״אֱמֶת״. (אָמַר) רַבִּי שְׁמוּאֵל בַּר נַחְמָנִי [אָמַר]: אֵלּוּ בְּנֵי אָדָם שֶׁקִּיְּמוּ אֶת הַתּוֹרָה כֻּלָּהּ מֵאָלֶף וְעַד תָּיו.
And that is the meaning of that which is written: “Slay utterly old and young, both maid, and little children, and women; but come not near any man upon whom is the mark; and begin at My Sanctuary” (Ezekiel 9:6). And it is written in that same verse: “Then they began with the elderly men who were before the house.” Rav Yosef taught: Read not: My Sanctuary [mikdashi], rather: Those sanctified to Me [mekudashai]. These are people who observed the whole Torah in its entirety from alef through tav. And immediately: “And, behold, six men came from the way of the higher gate, which lies toward the north, and every man with his weapon of destruction in his hand; and one man among them was clothed in linen, with a writer’s inkwell by his side; and they went in and stood beside the bronze altar” (Ezekiel 9:2). And Reish Lakish said: The letter tav is the last letter of the seal of the Holy One, Blessed be He, as Rabbi Ḥanina said: The seal of the Holy One, Blessed be He, is truth [emet], which ends with the letter tav. Rabbi Shmuel bar Naḥmani said: The letter tav teaches that these are people who observed the entire Torah from alef through tav.