(יא) אַבְטַלְיוֹן אוֹמֵר, חֲכָמִים, הִזָּהֲרוּ בְדִבְרֵיכֶם, שֶׁמָּא תָחוּבוּ חוֹבַת גָּלוּת וְתִגְלוּ לִמְקוֹם מַיִם הָרָעִים, וְיִשְׁתּוּ הַתַּלְמִידִים הַבָּאִים אַחֲרֵיכֶם וְיָמוּתוּ, וְנִמְצָא שֵׁם שָׁמַיִם מִתְחַלֵּל:
(11) Abtalion used to say: Sages be careful with your words, lest you incur the penalty of exile, and be carried off to a place of evil waters, and the disciples who follow you drink and die, and thus the name of heaven becomes profaned.
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.
§ When the eye of a Torah scholar has not sufficiently seen them, he is not certain about them, and we do not return a lost item to him, as Rav Yehuda says that Shmuel says: With regard to these three matters alone, it is normal for Sages to amend their statements and deviate from the truth: With regard to a tractate, if he is asked whether he studied a particular tractate, he may humbly say that he did not, even if he did. And with regard to a bed, if he is asked whether he slept in a particular bed, he may say that he did not, to avoid shame in case some unseemly residue is found on the bed.
And he can lie with regard to a host [ushpiza], as one may say that he was not well received by a certain host to prevent everyone from taking advantage of the host’s hospitality. What is the practical difference that emerges from this statement with regard to matters in which Torah scholars deviate from the truth? Mar Zutra says: The practical difference is with regard to returning a lost item on the basis of visual recognition. If we know about him that he alters his statements only with regard to these three matters, we return the lost item to him, but if he alters his statements with regard to other matters, we do not return the lost item to him.

