Bir fincan kahvenin kırk yıl hatırı vardır

Literally: A cup of coffee has forty years of memory

Example: “Komşuyu kahveye çağır; bir fincan kahvenin kırk yıl hatırı vardır.” — Invite the neighbor for coffee; a single cup is remembered for forty years.

Origin: Popularly traced to a specific, often-retold story about a wise man named Yusuf from Üsküdar and a Greek fisherman named Stelyo. In one version, an Ottoman officer at a coffeehouse orders Yusuf to serve everyone present a rich, generous coffee except for the Greek patron sitting nearby — but Yusuf quietly serves Stelyo anyway, insisting privately that this particular coffee is on him and fully permissible regardless of the officer's order. Years later, when a Greek uprising breaks out on Samos in 1905 and Yusuf, now serving as a soldier, is taken prisoner during the fighting, Stelyo arranges his safe, secret passage back to Istanbul in return. The two men's friendship reportedly continued for another 35 years afterward, marked every year by a visit and, always, a shared cup of coffee — the story that gave rise to the now-proverbial claim that even one cup of coffee carries forty years' worth of goodwill and remembered debt.