જાણ્યું ઝેર ખવાય નહીં.

jāṇyuṁ jhēra khavāya nahīṁ.

Literally: Knowing it to be poison, one does not consume it.
What it means: No sensible person deliberately walks into a known danger or self-destructive situation.

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.