સમ ખાય તે સદા જુઠો.

sama khāya tē sadā juṭhō.

Literally: He who takes an oath is always a liar.
What it means: People who feel the need to swear oaths are usually hiding the truth.

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.