ઊંદર બિલાડીને મેળ આવે, તો ઘરધણીને સુખ આવે નહીં.

ūṁdara bilāḍīnē mēḷa āvē, tō gharadhaṇīnē sukha āvē nahīṁ.

Literally: If the mouse and cat come to an agreement, the house owner will not have peace.
What it means: When two natural enemies collude, the person in charge suffers.

Also said as

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.