ડાહ્યા ભૂલે નહીં, ભૂલે ત્યારે ભીંત ભૂલે.

ḍāhyā bhūlē nahīṁ, bhūlē tyārē bhīṁta bhūlē.

Literally: The wise do not make mistakes; when they do, they mistake a wall.
What it means: Said when an otherwise highly intelligent or capable person makes an incredibly obvious or massive mistake.

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.