The Art of Lying

(7) Keep thee far from a false matter; and the innocent and righteous slay thou not; for I will not justify the wicked.

For a teacher has said : Teach your tongue to say, "I do not know," lest you invent something and be trapped.

Rather it is to say that your "yes" be yes and your "no" be no. Abaye said that means one should not speak one thing with the mouth and another with the heart.

This is the penalty for the liar, even when he tells the truth, no one believes him

Rabban Shimon ben Gamliel used to say: On three things does the world stand: On justice, and on truth, and on peace, As it is said: “Judge with truth, justice, and peace in your gates.”

(10) One should not say to [a merchant], "How much is this object?" if he does not want to buy....

(7) מדבר שקר תרחק, the Torah addresses the judge, telling him to stay clear of anything which could create the impression that he has dealings with something corrupt. Our sages enlarge on this, cautioning that the judge must be careful with all his utterances so that a liar cannot exploit his words for his own nefarious purposes. (Avot 1,9)

1. If a person is sitting at a din Torah and sees an angle that the dayanim don’t see, if he keeps quiet, he violates מדבר שקר תרחק.
2. If a person sees his rebbe make a mistake and waits to tell him so that the whole shiur can be stated in his name, it is a violation of מדבר שקר תרחק.
3. One who is owed a hundred dollars cannot claim that he is owed two hundred so that the final number settles on a hundred.

How do we dance before the bride? [How do we praise the bride to the groom?].

Beit Shammai says, “[We praise and describe] the bride as she is.” [since the Torah says 'Distance yourself from falsehood]

But Beit Hillel says, “[In all cases we give praise and say] that the bride is pleasant and kind.” [for the sake of peace]... From this originates the saying of the sages: "At all times should man's disposition be pleasant in associating with men."

R' Ila said in the name of R'Eliezer in name of R'Shimon: a person is permitted to change his words for the sake of peace. R'Natan said: it is a Mitzvah to do so!

(12) And Sarah laughed at herself, saying: "After I have become barren, shall I again become young? Plus, my husband is old!" (13) And the God said to Abraham: "Why is it that Sarah laughed saying 'Am I truly going to bear a child, even though I have aged?'...

The school of Rabbi Yishmael taught in a beraisa "Great is peace, for even The Holy One, Blessed is He alters [the truth] for its sake. Originally it is written "And my husband is old!" And in the end it is written "And I am old!" (Bereishit 18:12-13)

One may vow to murderers and thieves and [self-appointed] tax collectors that [something] is terumah (the tithe to the cohen), even if it isn't terumah; [or] that they are property of the king, even if they aren't property of the king.

Rav Yehuda said in the name of Shmuel, "In only these three matters is it the practice of the rabbis to deviate in their speech [from the truth]: regarding a section of Torah, modesty, and hospitality.

Rabbeinu Yonah (d. 1263) writes that when a lie does not affect anyone else negatively it is less serious and therefore, the rabbis permitted those types of lies in certain cases. If the consequence of the lie is insignificant, the value of peace overrides the prohibition.

Rambam (1138-1204) codifies the Gemara that one can return an aveida to someone who never lies. Among the permissible exceptions are the three cases in the Gemara plus lying for the sake of peace. {‏9}

(7) A scholar should not shout and scream while he speaks, like animals and beasts. And he should not raise his voice excessively. Rather he should speak pleasantly with all people. But in speaking pleasantly... And he should not distort [the reality] with his speech, not adding and not subtracting [from the truth], except in words of peace and the like. The principle is: he should not speak except in words of wisdom or kindness and so on.

The Gemara records a story about Rav whose wife would always prepare dinner the opposite of his request. When his son Chiya grew older, he figured out what his mother was doing and he would tell her that his father wanted A when he really wanted B so that she would serve B. Rav found out about it and praised Chiya’s wisdom but told him not to do it because למדו לשונם דבר שקר.

R. Zera further said: One should not promise a child to give him something and then not give it to him, because he will thereby teach him lying, as it is said, “They have taught their tongues to speak lies” (Jer 9:4).

When a man is brought before the [heavenly] court he is asked: "Were you trustworthy in business? Did you set time for Torah [study]? Did you try to have kids? Did you hope for the Messiah? Did you argue intelligently? Did you understand things based on other things?"