«إِنْ كَلْتِ الرُّمَّانْ اِفْرِدْ حِجْرَكْ وِانْ كَلْتِ الْبَطِّيخْ لِمِّ هْدُومَكْ»

The proverb contrasts what is harmless with what is likely to cause damage. One need not take defensive measures against a person or thing known to be sound, whereas caution is sensible around what may bring trouble.

Using the risk of food staining clothes as a figurative contrast, it advises judging risks by their nature rather than meeting everything with equal suspicion. Trustworthy people or situations need not prompt anxious guarding; unreliable or harmful ones warrant care and distance.

Use it to advise discriminating trust: be open with what has proved benign, but protect yourself when dealing with someone or something likely to create problems. Its domestic food image makes the warning vivid rather than abstract.