There are friends who remain true and trustful under all circumstances and there are friends who remain with you only desiring the good. Islam urges to  have cordial relations with others and to avoid corruption and the harmful  effects of the company of the wicked and the mischievous, strictly  forbidding every kind of contact and intimacy with them. The first kind of  friend are very few, and their friendship is like a mirror to you. In deed,  we must be fair to our friends, and must want for them that which we want  for ourselves. Nabiy Muhammad (Sallallahu Alayhi Waalihi  Wa Salam) said,"A  true believer is a mirror to his brother. He prevents him from any harm."  Friends wish well for their friends, and feel a strong grief when they see  them in any kind of distress or suffering. They work hard by all means, by  their wealth and their hands to restore the rights of their friends, and  give them all the help they need. They keep the secrets of their friends.  This kind of friendship is the basic necessity of social life. Nabiy  Muhammad (Sallallahu Alayhi Waalihi  Wa Salam) said,"A person follows the  ways and conducts of his friends." On the other hand, one encounters fools, avaricious, people cowards, and liars. The fool wants to help others, but  cause more harm to them despite good intentions. The avaricious one takes  but does not give back to anyone. The coward flees at the smallest danger,  abandoning everyone. And the liar does not benefit others, brings animosity  and resentment, and causes serious damage to others. Also, the liar is not  trusted even if he/she is telling the truth. It is reported,"As for a liar,  life with him can never be pleasant for you. He carries tales from you to  others and from others to you. If he gives you a true report, a false one  follows it. His reputation is slurred. So much so that when he says  something true, nobody believes him. Due to the enmity which he entertains  in his heart for people, he estranges them from one another and creates  malice in their hearts. Be careful and do your duty to Allah."  These kinds of individuals might call themselves as your friends, but they do more ill-service to you as well as to the society and in the long run. It is adviced,"Avoid the company of the vicious, because your character would pick  up their degenerate and deviant qualities without your knowing it." The  Glorious Qur'an says,"O woe is me! Would that I had not taken
such a one as  my friend." 25:28

There are many characterizes of true friends: their heart and face should be alike, they should be honest with their friends and show them both the good  and the bad side: wealth and children should not change them; they should  help whenever able to do so, and they should not leave their friends during  difficulties.

To choose a friend, one must assess his real worth. One must bear in mind  that temperaments and personalities are associated with one, relationships  with others. Nabiy Muhammad (Sallallahu Alayhi Waalihi Wa Salam)  said,"Every Muslim should try to select the best companion for the life  span. A companion could be a friend from the same gender. If the companion  is to be from the other gender, then that companion should be a spouse to  live together within the confines of rules and regulations."  Our beloved  Nabiy (Sallallahu Alayhi Waalihi Wasalam) encouraged us to select a good  friend with whom to share our feelings. He said,"Don't take a companion  unless he is a believer; and don't let your food be eaten except by a godly  person." Also, one must take a friend for who he or she is as an individual,  and not force them to conform with one's warp and ideas, so long as  everything remains within the boundaries of Islam.

Muslims are advised by the Nabiy (Sallallahu Alayhi Waalihi Wasalam) to select a good friend to associate with, and to have him as a social companion in life. By selecting a good companion, to be a friend, a Muslim  enriches his/her life. Nabiy (Sallallahu Alayhi Waalihi Wasalam) said,"The  similitude of a good companion is like an owner of musk; if you don't get  anything, you will get the smell of it. The similitude of a bad companion is  like the blacksmith's bellows; if you are not affected by its black dirt,  you will be touched by its smoke."

Islam approves associating with individuals who have violated moral and social laws for the purpose of helping them through beneficial guidance. Friends of the right path father and discuss what is beneficial, but not  vain. Friends love the souls and smells of their friends. Friends sympathies  with their friends and they comfort each other. Friends exert each other  toward piety and righteous deeds. Nabiy Muhammad (Sallallahu Alayhi Waalihi   Wa Salam) said,"Fear Allah and help each other for the sake of Allah. Have  mercy upon each other. Visit each other and remember our matter and keep it  alive."

However, one who keeps company for the sake of helping a friend, would have  fulfilled the rights of companionship in the worthiest manner. It is  reported,"When someone observes a friend taking a wrong and sinful course  and, while possessing the capacity to restrain him, does not do so out of  indifference, he has actually betrayed his friend."

Today, in this world of ignorance and personal desires, there are few who  keep their friendship. Hence, everyone should be careful in choosing  friends, and study the character of those with whom they wish to develop  terms of friendship.