પારા પુંઠથી નિકળે, માંખી મુખથી બહાર.

pārā puṁṭhathī nikaḷē, māṁkhī mukhathī bahāra.

Literally: Mercury comes out from behind, and a fly comes out from the mouth;
What it means: Secrets or ill-gotten gains cannot be kept hidden for long and will eventually expose themselves.

Also said as

ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1923) · 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.