દોહરો—દુર્જન તે દુર્જન હોય, સજ્જન કેમે ન હુવંત;

dōharō—durjana tē durjana hōya, sajjana kēmē na huvaṁta;

Literally: A wicked person remains wicked; they never become good by any means.
What it means: An evil nature cannot be transformed into virtue.

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.