«اِلزِّينْ مَا يِكْمَلْشْ»

Here زين means someone fine or good-looking, not the personal name Zain. The saying holds that no person who is truly fine, whether in appearance or in character, will turn out to be perfect in every respect. A single shortcoming is expected rather than surprising.

It applies to someone handsome who has one marring feature, and equally to a person of good conduct who strays in some particular habit. That one lapse keeps them from complete perfection, yet it does not cancel the merit they otherwise possess.

Say it when someone admired for looks or conduct reveals a blemish or lapse. It gently acknowledges the flaw rather than condemning the person, excusing it as only human or wryly noting that even the best person falls short somewhere.