LEV161 Based on a Torah verse, the Talmud declares that lying in all business activities is forbidden, i.e., that your "yes" should really be a yes, and your "no" should truly be a no (Leviticus 19:36, Bava Metzia 49a). A sixteenth century Rabbi writes that telling the truth and not lying in a Jew's everyday routine is an actual Mitzvah, a commandment (Sefer Charedim, Mitzvot Asei Bipeh, 26). The Talmud describes four groups of people who are denied the Divine Presence, and one of them is people who lie regularly (Sotah 42a). By using one extra letter, the Torah teaches us to be exact in our words and never lie, even in small and obvious matters. Regarding a house that was suspected of being ritually impure (that had to be validated by a Kohen-Priest to make it official), a Rabbi seeing the home would initially say, "It appears to have a ritual impurity," even though it was clear to that Rabbi that the home was impure. However, since it could not become officially ritually impure until the Kohen said so, the Rabbis added the extra letter Kaf signifying "it appears" in order not to tell even a mild untruth (this verse with Rashi and Gur Aryeh commentaries). Maimonides especially warns Torah scholars to be extremely careful in their words, and never even hint at an untruth (Maimonides, Hilchot De'ot 5:7,13). Rabbi Yisrael Meir Kagan (known as the Chafetz Chaim), who became famous for the way he taught Jews how not to misuse their words, says that a Jew who lies is subject to lose all of his or her possessions as well as other harsh punishments, as the sin of lying encompasses many severe sins in Judaism (Sefat Tamim, chapter 2). A person who habitually lies, says the Talmud, will never be taken seriously or be believed, even when he or she tells the absolute truth (Sanhedrin 89b). The prophet Isaiah implies that once a person's lips are impurified by repeated lying, (Isaiah 6:5). On this verse, Chafetz Chaim points out that the impurity of lying stays with the Jew longer than any other type of impurity in Jewish law, especially regarding the impurity related to the head of a human being (Kavod Shamayim 2:6).