«مَسِّكُوا الْقُط مُفْتَاحِ الْبُرْجْ»

The image is of people who hand the key of a pigeon house to a cat. The cat has always eyed the birds, and once it can get in freely it will leave none of them alive. The folly lies in the handover itself, since the outcome was easy to foresee.

Figuratively, the proverb condemns placing control of something in the hands of a person who is unfit to protect it and who has already shown a hunger for it. It warns that such a choice amounts to inviting the loss, and it holds the people who granted the access responsible.

Use it to criticize a decision that puts resources, property, or authority under the control of someone who has long coveted them and cannot be trusted. The criticism falls mainly on those who made the choice, so it is not simply an insult aimed at the untrustworthy person.