“Is it lawful to divorce one's wife for any cause?”
Then some Pharisees came and tested Him by asking, 'Is it lawful for a man to divorce his wife for any reason?'… Now I tell you that whoever divorces his wife, except for sexual immorality, and marries another woman, commits adultery. (Matthew 19:3–9 BSB)
What it sounds like today
A neutral bit of paperwork.
The cultural key
Refers to the get of Deuteronomy 24:1, granted for 'some indecency,' and that phrase was the hottest legal debate of Jesus' generation. The school of Hillel read it as almost anything (a spoiled dinner qualified, per the Mishnah); the school of Shammai restricted it to sexual immorality. A divorced woman in that economy often faced destitution. 'For any cause' is the Hillelite school's slogan almost verbatim; the test invites Jesus to endorse a party. He instead goes behind Moses to Genesis ('from the beginning it was not so'), reclassifies the Deuteronomy 24 certificate as a concession 'because of your hardness of heart,' and lands nearer Shammai with the exception clause. The disciples' horrified reaction ('better not to marry!') measures how permissive the prevailing practice had become.
Recovered meaning
Jesus enters a live courtroom debate and shuts the wide door: the certificate was a concession protecting the woman, not a license for men to discard wives at will.