'Umar Ibn al-Khattab رضي الله عنه said, "Accompany the brothers of truthfulness (sidq) and live under their wing, for they are an adornment in times of ease (rakha') and an asset in times of calamity (bala'). Think the best about your brother unless he comes to you with something that angers you. Stay away from your enemy. Be cautious with your friend except for those who are trusted (amin), and no one is trusted save those who fear Allah. Do not accompany a sinner (fajir) and learn from his sinfulness as a result, and do not tell him your secrets. Consult (only) those who fear Allah regarding your affairs." [The Refinement Of Character, pg. 66-67, Imam Ibn Qudamah al-Maqdisi رحمه الله]