The general prohibition against verbal abuse: Bava Metzia 58b, 59a
Saying, "I was kidding [Mishateh Ani Bach]": Yevamot 106a (to fool a man into performing the Chalitzah-Rite ending a woman's Levirate Bond)
Inquiring about the price of an item, when one has no intent to buy: Bava Metzia 58b
Handling merchandise when one doesn't have money, thus chasing away real customers: Pesachim 112b
Mis-leading someone who is seeking merchandise, sending him to someone who doesn't sell it: Bava Metzia 58b
Reminding a person of his sinful past, when he has repented: Bava Metzia 58b
Reminding a descendant of converts of his parents' pre-conversion deeds: Bava Metzia 58b
Telling a suffering person that his suffering is punishment for his sins: Bava Metzia 58b
Special prohibitions against abusing a person who has converted to Judaism: Bava Metzia 59b
Beyond the law
Verbal abuse is worse than financial abuse: Bava Metzia 58b
Being especially careful when speaking with one's wife, due to her native sensitivity: Bava Metzia 59a
Gd's immediate and direct response to victims of onaah, even when all avenues to Gd are closed: Bava Metzia 59a, 59a-b Gd always sees onaah: Bava Metzia 59a
