Choosing Your Companions
Umar ibn Al Khattab once said to his companions, "Make a wish." So one of them said, "I wish that this house was filled with gold so that I could spend it for the sake of Allah and give it in charity." Another said, "I wish it was filled with precious stones so that I could spend them for the sake of Allah and give them to charity."
Umar again said "Make a wish."
His companions didn't know what else to say.
Then he said, "I wish that it was filled with men like Abu Ubaydah ibn Al-Jarrah, Muadh ibn Jabal, Salim the freed slave of Abu Hudayfah and Hudayfah ibn Al-Yaman, so that I may employ them in the service of Allah."
These and other sahaba were his companions and brothers in Faith. Umar used to say: "you should look for sincere companions, for you will be happy with them; they will be a source of pleasure at times of ease and a support in times of calamity. Think positively of your brother until he does something that justifies your keeping away from him, and keep away from your enemy, and beware of your friend except those who are trustworthy, and there is no one who is trustworthy except those who fear Allah. Do not keep company with an evildoer lest you be influenced by his evil, and do not tell him your secrets. Consult those who fear Allah about your affairs."