Who can be your worst friend?

worst-friend
Imam ‘Ali (a.s.) said:
“شَرُّ إخْوانِكَ مَنْ داهَنَكَ فى نَفْسِكَ وَ ساتَرَكَ عَيْبَك”

Translation
Your worst friends are those who flatter and talk with you superficially and conceal your faults.1

Brief Description
Escaping the realities and concealing the truths neither solves any problem nor is it a service to anyone. Therefore, friends who refrain from constructive criticism and from urging corrective actions and, instead, hide their friend’s faults for his false satisfaction, or misrepresent it as goodness, have failed to be faithful in friendship. They have also committed a great treachery that may cause serious damage to the prestige, reputation, honor and prosperity of their friend.[divider]
•    1. Ghurar al-Hakam