The Sages are extremely critical of certain forms of lying, flattery and hypocrisy.

King Yannai said to his wife: Do not fear the Pharisees, and those who are not Pharisees. Rather, beware of the hypocrites who appear to be Pharisees, whose actions are like the act of Zimri and yet they request a reward like Pinhas.

Rava said: Any Torah scholar whose interior does not correspond to his exterior is not a true Torah scholar.

Rabbi Elazar says: As for any person who has the trait of flattery, even fetuses in their mothers’ wombs curse him…. Rabbi Elazar says: Any person who has the trait of flattery falls into Gehenna…. Rabbi Elazar says: Anyone who flatters another ultimately falls into his hands; if he does not fall into his hands, he falls into his children’s hands. And if he does not fall into his children’s hands, he falls into his grandchild’s hands…. Rabbi Elazar says: Any congregation in which there is flattery will ultimately be exiled…. Rabbi Yirmeya bar Abba says: Four factions will not greet the Divine Presence: the faction of scorners, the faction of flatterers, the faction of liars, and the faction of slanderers. (Sota 22b; Yoma 72b; Sota 41b–42a)