Socrates vs Epictetus: on suicide

Socrates begins an argument against suicide, reminding his friend that it “is held not to be right.” On what grounds?

[Socrates and Epictetus, Wiki Commons; essay #248 in my “Philosophy as a Way of Life” series]

“Why, said Socrates. Is not Evenus a philosopher?
I think that he is, said Simmias.
Then he, or any man who has the spirit of…