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.

The Holy Quran is said to be "the highest miracle of Islam". But why would a book turn out to be the proof of Prophet Muhammad’s (PBUH) prophethood? What does it reveal about Islam's attitude toward the issue of learning or seeking knowledge?  How does a true Muslim seek knowledge?

There are many verses in the Quran about acquiring knowledge. The very first verse of the Quran that was sent to our Prophet starts with an imperative form of the verb "read" (Ighra) [1]. Literacy and having knowledge is so important in Islam that Quran equals illiteracy to being in darkness [i]. Accordingly, it is the duty of any Muslim to try to learn. Besides, many Islamic scholars advise Muslims to strive for achieving knowledge. One of them is a quotation (hadith) from Prophet Muhammad (PBUH&HP): “Seek knowledge, even if it is in China”. Considering the distance between the Arabian Peninsula (where the Prophet lived) and China as well as the lack of transportation 14 centuries ago, one can imagine how arduous it was to travel there. In addition to many life-threatening dangers, it is no exaggeration to say that it took several months to arrive there. This shows the emphasis on the importance of learning.

When the prophetic mission of Prophet Muhammad (PBUH&HP) started, most people in his land were illiterate, so, he asked the literate ones to teach Muslims; even prisoners of war were granted freedom provided that they taught literacy to at least ten Muslims. It has been said that once, the Prophet (PBUH&HP) entered a mosque and saw two groups of people; one group was praying and the other was sharing knowledge. He stated that both of them were doing a good job, and then continued his speech by saying that he was sent to people by God “to teach” them. So he went and sat in the second group [2]. When Prophet Muhammad (PBUH&HP) was alive, there were places like schools where both women and men had the freedom to take part in classes. And, different fields of knowledge were learned including religion, literature, poetry, rhetoric, medicine, astronomy, etc [3].

A human being is curious by nature. We have been created with an inquiring mind. It has been said that all human beings are bestowed a gift, that is the brain as well as the desire for learning. The desire to learn is in our nature [4]. In Islamic instructions, there is a huge emphasis on the value of seeking knowledge. It has been quoted from Prophet Muhammad (PBUH&HP): “Seek knowledge from the cradle to the grave”. It is a must for every Muslim regardless of their age, race, or gender [5]. All people must have the ability and liberty to learn, teach, exchange, and share information. It does not matter from whom you are learning. As long as they have the knowledge, it would be perfect. There is an Islamic hadith from the fifth Imam of Muslims, Imam Muhammed Al-Bagher (AS), quoted from Jesus Christ (AS) saying that: “Learn knowledge from someone who has it and does not look at their deeds.” There is no kind of prejudice whatsoever in choosing the teacher. The only important thing is the learning itself. Besides, ignorance has been known as the root of many miseries; and knowledge is like a vast amount of treasure that never runs out.

Notes:
[i]. (13:16)

References:

1. Ahamiyate Danesh-Andoozi az Nazare Eslam Akhlagh va Irfan 
2. Morteza Motahari, "Talim va Tarbiyat Dar Eslam [Education in Islam]", Sadra, p. 22, 2008.
3. Soheyla Jalali, Derakhsheshe Zanane Mosalman Dar Arseye Elm va Farhang Dar Sadre Eslam Pajooheshgahe Oloom va Farhange Islami
4. Morteza Motahari, "Moghadame'I bar Jahanbiniye Eslami. [An Introduction to Islamic Ideology]", Sadra, p. 274, 2004.
5. Faeze Azimzade Ardebili, Hghe Amoozeshe Zanan Dar Eslam va Gharb [The Right of Learning for Women from Islamic and Western Viewpoint