એવા સાચા કે જ્યાં બોલે ત્યાં ખાય તમાચા.

ēvā sācā kē jyāṁ bōlē tyāṁ khāya tamācā.

Literally: So truthful that wherever he speaks, he eats slaps.
What it means: Being brutally honest at the wrong time or place will only get you into trouble.

Also said as

ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1923) ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1921) · read from the scan by machine — the Gujarati itself is unchecked · English is machine-made and nobody has checked it yet

Heard it differently, or know we've got the sense wrong? Tell us — that is exactly the kind of correction this needs.