'Immorality' in the Bible

But I say to you that everyone who divorces his wife, except for a matter of sexual immorality, causes her to commit adultery, and whoever marries a divorced woman commits adultery.

For from the heart come evil plans, murder, adultery, sexual immorality, theft, false witness, abusive speech.

Now I say to you that whoever divorces his wife, except on the basis of sexual immorality, and marries another commits adultery, and whoever marries her who is divorced commits adultery."