Friendship with wicked person should be avoided

दुर्जनेन समं सख्यं प्रीतिं चापि न कारयेत् |
उष्णो दहति चांगार: शीत:कॄष्णायते करम् ||
Meaning : One should avoid friendship or warm relationship with wicked person. (like a coal). If hot (he) burns (your hands) if cold, (he) blackens (your) hands. (i.e. if he is bad to you, they will surely cause some problem to you, but even if he is good to you, contact alone will cause some problem).