વાઘને વેળાનું નહીં.

vāghanē vēḷānuṁ nahīṁ.

Literally: A tiger has no fixed time.
What it means: Said of unpredictable, dangerous persons or calamities that strike without warning at any hour.

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.