નેબ જાય ને એબ રહી જાય.

nēba jāya nē ēba rahī jāya.

Literally: The grace goes and the blemish remains.
What it means: Good deeds or beauty are quickly forgotten, but a single mistake or defect is remembered forever.

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.