What is the legal test for dismissal of a servant for verbal abuse by their master?

In 26 Cyc, p. 986, it is stated that a servant is not justified in abandoning his contract before the expiration of the term unless good and just causes exist therefor, and that, generally speaking, any breach of the express or implied provisions of the contract of employment by the master, or any act or neglect on his part which is prejudicial to the safety, health, comfort, morals or reputation of the servant will be deemed sufficient grounds for abandonment. In the notes to the above it is stated that a mere disagreement or rude remark by the master is no justification, neither is harsh language by the master. I cannot find any case in which it has been held that mere abuse by words or insulting language are sufficient grounds for the servant abandoning his employment. I quite realize that the relationship of master and servant is greatly different from what it was in early days. Formerly, a servant was practically a mere chattel; the master could do with him practically what he liked. He could chastise him. But conditions have greatly changed, and I apprehend that conduct which would not in the early days have justified a servant in abandoning his employment would be held to-day as sufficient grounds for abandonment. There are cases in which it has been held that a servant may be dismissed for gross insolence or rudeness to his master, but it has been held that a single instance of insolence on the part of a servant is not sufficient ground for dismissal. Edwards v. Levy, 2 F. & F. 94.