સોળે સાન, વીશે વાન, ન આવ્યાં તે ગધા સમાન.

sōḷē sāna, vīśē vāna, na āvyāṁ tē gadhā samāna.

Literally: Wisdom at sixteen, beauty at twenty; if they do not come by then, one is like a donkey.
What it means: A person must acquire common sense and maturity by young adulthood, or they will remain foolish forever.

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.