A Torah Scholar ought to lie if asked about the hospitality of his host, lest people take advantage of the host: Bava Metzia 24a
Not informing a sick person of a relative's death: Moed Katan 26b
In dealing with one's children: Succah 46b
On one's taxes: Nedarim 28a
Dishonest weights and measures
HaShem warns us: I knewwhether an Egyptian child was a firstborn, I will also be able to tell if you lend money on interest through a third-party nochri, if you store your weights in salt, and if you use indigo instead of techelet on your tzitzit: Bava Metzia 61b
One may not keep dishonest weights and measures, even if one never uses them: Bava Metzia 61b
Storing one's weights in salt: Bava Metzia 61b
If partners wish to divide land, measuring for one in the winter and for one in the summer, with a rope which is vulnerable to seasonal shifts: Bava Metzia 61b
Measuring out liquids and including the foam at the top: Bava Metzia 61b
Beyond the Laws
One must always make certain that his "Yes" and "No" are honest: Bava Metzia 49a
The Destruction of Jerusalem was for the lack of honest people: Shabbat 119b-120a
Hashem hates people who speak one thing and think another: Pesachim 113b
Lies are more popular than truth, but lies cannot stand: Shabbat 104a
Liars are not accepted in the "inner area" of HaShem: Shabbat 149b Rain as a Divine reward for honesty: Taanit 8a
The greatness of honesty and trust in Gd: Taanit 8a
One who falsely claims his assets belong to another party, to avoid appearing rich, will complain in court and they won't be able to help him: Bava Metzia 75b
