મોઢે મીઠી વાત, પાછળ વગેણું કરે;

mōḍhē mīṭhī vāta, pāchaḷa vagēṇuṁ karē;

Literally: Sweet words to the face, slander behind the back.
What it means: Hypocritical acquaintances praise a person directly while vilifying them to others.

Also said as

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.