~ Ein gut Gewissen hat der Mann ~
This blue/gray, salt-glazed, stoneware stein without lid is marked with the Merkelbach & Wick logo, ca. 1900. The verse is translated literally for educational purposes and is similar to other verses with the same theme. (See translation: Ein wackerer Zecher steckt sich fein) It means that before leaving one's house, he should have the key in hand so he can get back in, especially after drinking.
Ein gut Gewissen hat der Mann
der den Hausschlüssel in der Tasche fühlen kann.
A good knowledge has the man
who can feel the house key in (his) pocket.
Translation: Roy De Selms
Photo credit: Unknown