«زَيِّ الْجُوزْ مَا يْجِيشْ إِلَّا بِالْكَسْرْ»

The saying compares a certain kind of person to a walnut: whatever is worthwhile inside stays locked behind a hard shell until someone breaks through it. Soft approaches achieve nothing, and only firm, forceful treatment gets results.

The image treats the breaking as a means rather than an end: the shell is cracked so the good part can finally be reached. Applied to people, strict handling becomes the step that brings someone into line and draws out what is good in them.

Fits remarks about someone who ignores polite requests and gentle persuasion and only cooperates under pressure or sternness. Use it to characterize a stubborn person, not a situation. Because it approves harsh handling, applying it to a real person can sound like justifying coercion or rough treatment of the vulnerable.