Human beings by nature are social creatures, in need of companions and friends. Most of our lives depend on interactions with others, and man is therefore compelled to live in society and with other individuals. Friendship in Islam is considered one of the Divine blessings through which one overcomes loneliness and solitude.

Islam has placed tremendous importance on sociability and friendship. In the Quran [i], great emphasis has been placed on the concept of friendship because maintaining good company plays a pivotal role in shaping the life of the individual and it influences the path that will be chosen in life. Likewise, the Holy Prophet (PBUH&HP) and his Ahl al-Bayt (AS) on different occasions had clearly stated its importance, criteria for choosing a friend, characteristics of a good friend and the rights of a friend [1].

Friendship in Islam

Friends are an integral and important part of our social life as they contribute greatly to the development of one’s personality and they affect many aspects of our lives. Islam, in complete harmony with man’s nature, deals extensively both in the Quran and the narrations (Hadiths) of Prophet Muhammad (PBUH&HP) with the issue of friendship in Islam.

In the Quran, Allah says:

“On that day, friends will be one another’s enemies, except for the Godwary.” (43:67)

The Holy Prophet (PBUH&HP) while explaining the impact of friends says:

“Man is influenced by the faith of his friends. Therefore, be careful of whom you befriend.”[2]

Similarly, the commander of the faithful; Imam Ali (AS) says:

“Try to have as many as possible true friends, for they are the supplies in joy and the shelters in misfortunes” [3]

Choosing a Friend

Islam attaches great emphasis on the choice of a friend to be selected in life. For this purpose, it is expected that one should employ his/her judgment in a manner free from emotion and try to set aside the criterion for assessing his/her real worth. “One must know his/her inadequacies and weak points, his/her ideas, feelings, dislikes and infirmities. Ultimately, one must discover the human merits and desirable qualities that he/she carries in the depth of his/her spirit so that one may benefit from his/her outstanding virtues.”[4]

Therefore, for the great good or bad influences friends can have on the characters and personality of each other, it is important for every man of reason to choose friends that are characterized by good mannerism and behavior.

Meanwhile, in accordance with the sayings of the Prophet (PBUH&HP) and his Ahl al-Bayt (AS), a Muslim must avoid certain sets of people as friends: transgressor, hypocrites, foolish, liar, sinful, stingy, and disregardful to his/her relatives. Similarly, non-Muslims should not be taken as intimate friends or allies [5].

However, there is no hindrance for a boy having a girl as a friend or vice versa, so far as the Islamic regulations (such as the Islamic Hijab, avoidance of indiscriminate touching, etc.) are observed and they avoid any sinful act.

Characteristics of a Good Friend

In Islam, the followings are some of the characteristics to be looked forward to in a friend:

Intelligence
Faith
Honesty
Uprightness and well mannerism

Rights of a Friend

Following some narrations (Hadiths) [6], friendship entails certain trusts and duties. The one who observes them is a true friend while one who breach them is unworthy of friendship in Islam. Here are some of the rights of friends:

Respecting them and their personality [7]
Rendering material supports in the time of need [8]
Advising them when they need your advice [9]
Forgiving their shortcomings [10]
Concealing their lapses and faults from others [11]
Visiting them when they are sick [12]
Participating in their funeral when they die[13]

Conclusion

Concisely, friends are integral parts of our social life, and it is important to be selective in the choice of companions and friends. The righteous ones who lead one to righteousness in this world and prosperity in the Hereafter should be considered as friends. 

In contrast, hypocrites and ill-mannered individuals who are sources of plights in this world and in the Hereafter should not be taken as friends. Similarly, Islam teaches the Muslims to observe certain matters in friendly relations. This is because immoderation in this regard may lead to deplorable consequences and bring regret and pain.

Notes:

[i] (9: 71), (25: 27-29), etc.

References:

1. Al-Amidi, Ghurar al-Hikam, P. 177; Mustadrak Wasa’il, Vol. 5, chapter 42
2. Allamah Majlisi, Bihar al-Anwar, Vol. 74, P. 192.
3. Mahdi as-Sadr, The Ahlul-Bayt; Ethical role models, P. 290.
4. Mujtaba Musavi Lari, Ethics and Spiritual growth, P. 211.
5. (3: 28); (4: 144); (5: 51); (9: 23) etc.
6. Imam Ali Zayn al-Abideen, Treatise on Rights, Right 33 (The right of the companion)
7. Ibid
8. Kulayni, Al-Kafi, Vol. 2, P. 198, Hadith No: 8.
9. Al-Amidi, Ghurar al-Hikam, P. 775
10. Ibid
11. Ibid, P. 707
12. Allamah Majlisi, Bihar al-Anwar, Vol. 16, P. 233, Hadith 35
13. Kulayni, Al-Kafi, Vol. 3, P. 173.

The responsibilities of a Muslim towards family, relatives and other Muslims in general, were already reviewed in an article. Here one's responsibility in Islam towards neighbors, friends, and enemies are discussed.

The Responsibility in Islam Towards Neighbors 

Doing good to neighbors is highly emphasized in Islamic teachings: “Worship Allah and … be good to … the near neighbor and the distant neighbor” (4:36). Prophet Muhammad (PBUH&HP) advised Imam Ali (AS) to honor the neighbors, even if they are disbelievers (Kafir) [1]. Imam Ali (AS) said that Prophet Muhammad (PBUH) used to invite repeatedly to doing good to neighbors such that we thought he (PBUH) was going to consider an inheritance for them [2].

The rights of neighbors on one another as an important responsibility in Islam, are:

To honor them in their presence, and to help and care about them when they are absent [3]. It includes visiting neighbors when they are sick, to assist their funeral, and to offer them your tasty meals that smell good [4];
To keep their secrets. It means that not to look for their faults and errors. And, if ever you become aware of some of their faults, do not reveal them but try to conceal their deficiencies [3];
Do not leave neighbors alone in difficulties [3]; e.g., help them in case of financial needs [4];
Do not be jealous of them if God grants them some blessings [3];
Ignore their errors to yourself and forget about them. If ever they do wrong to you unintentionally, be patient and in peace with them [3];
Do not let others talk behind their back and reveal the deficiencies of your neighbors here and there [3].
Giving priority to the neighbors. It is narrated from Imam Hassan (AS) that Lady Fatima al-Zahra (AS) used to pray firstly for the neighbors and then for members of the family [5]. 

According to Imam Sadiq (AS), having good behavior and interaction with neighbors increases the provision (Rizq) [6]. Prophet Muhammad (PBUH) advised to respect neighbors as much as one should respect his\her mother [6] and he (PBUH) said: “God bless whoever does good to his\her neighbors” [7]. On the contrary, whoever sleeps peacefully at night while one of the his\her neighbors is hungry, God will deprive him of his blessings on the judgment day [8]. The same will happen to whoever annoys his\her neighbors [1]. 

Take your time and think about these attitudes towards the neighbors. Life will be surely much agreeable and peaceful if we improve our social interactions with our neighbors within the Islamic framework.

The Rights of Friends and Companions

Having a good companion is known as a blessing; on the contrary, a bad one is like a disaster [9]. Friends and companions have certain rights one over the other including:

To interact with them with generosity as much as you can, otherwise, be fair to them [3];
To be smiling when you meet them and to receive them modestly [3];
To respect them as they respect you [3];
To be the first one who does good to the other one, otherwise, try to compensate properly [3];
To help them in difficulties and whenever they are in need, as Imam Ali (AS) advised to [10];
To hold them in great affection according to Imam Ali (AS) [11];
Not to reveal their deficiencies and mistakes;
To encourage them in obedience to God and to prevent them from committing sins [3];
To be honest with them and not to cheat [3]; e.g., nor to talk behind their back neither to reveal their deficiencies and to guard their secrets;
To be trustworthy whenever they rely on you [3].

The Responsibility in Islam Towards the Enemies

The enemy here means a person whom one is in conflict with. There are some recommendations in Islamic resources on how to treat enemies and what is one's responsibility in Islam towards them:

To be fair with them [12]. According to Imam Sadiq (AS), a real believer (Mu'min) does not oppress his\her enemies [13];
To testify in favor of the enemies if they are right [14] even if your testimony is against yourself [3];
To keep the promises you made to your enemies [15];
To forgive and tolerate them, if possible [3]. According to Imam Ali (AS), there is a virtue in forgiving enemies [16];
To talk nicely and shortly with whoever you have complained of [3], to argue with them in a way that is best (16:125), and not to ignore their rights if ever you are wrong [3].

References:

1. M. Shoueiri “Jami’ al-Akhbar”, p. 84.
2. Shaykh al-Kulayni, “Al-Kafi”, vol. 7, p. 51.
3. Imam Zayn al-'Abidin (AS), “Treatise On Rights (Risalat al-Huquq)”.
4. responsibility towards others
5. Shaykh al-Saduq, "Ilal Al-Shara'i", p. 181
6. Shaykh al-Kulayni, “Al-Kafi”, vol. 2, p. 666.
7. Shaykh al-Saduq, “Al-Amali”, p. 288.
8. Shaykh al-Kulayni, “Al-Kafi”, vol. 2, p. 668.
9. “Ghurar al-Hikam wa Durar al-Kalim”, T. 4719-4720.
10. “Nahj al Balaqa”, p. 494.
11. “Ghurar al-Hikam wa Durar al-Kalim”, T. 9665.
12. Ibn Shu’bah, “Tuhaf al-Uqul”, p. 88.
13. Shaykh al-Kulayni, “Al-Kafi”, vol. 1, p. 47.
14. Shaykh al-Saduq, “Sifat al-Shia”, p. 24.
15. “Nahj al Balaqa”, p. 53.
16. “Ghurar al-Hikam wa Durar al-Kalim”, p. 435.