One of the necessary aspects of this brotherhood is love. That is, it is an obligation upon all Muslims to love their brother Muslims. In fact, they should love them in a manner similar to the way they care for themselves. As the Prophet, may the mercy and blessings of God be upon him, said:
“None of you truly believes until he loves for his brother what he loves for himself.” (Saheeh Al-Bukhari, Saheeh Muslim)
A second necessary aspect of this brotherhood is mutual support, aid and assistance. When his brother is being oppressed or wronged, he comes to his aid and assistance with his wealth and soul, if possible. This is described, for example, in the following verses:
“And what is wrong with you that you fight not in the Cause of God, and for those weak, ill-treated and oppressed among men, women and children, whose cry is, ‘Our Lord! Rescue us from this town whose people are oppressors, and raise for us from You one who will protect, and raise for us from You one who will help.’” (Quran 4:75)
A third essential aspect of this Islamic brotherhood is mercy and tenderness between the believers. This goes beyond a simple love for one another but it means that each brother feels in his heart for what his brother is going through. The Prophet described the Muslims in the following fashion:
“The similitude of believers in regard to mutual love, affection, fellow-feeling is that of a body; when any limb of it aches, the whole body aches due to fever and sleeplessness.” (Saheeh Muslim)
A final necessary component of our brotherhood is common acts of courtesy. True brotherhood has to be put into practice; it cannot simply be a statement of the tongue. One amazing and beautiful aspect of Islam is that it does not leave matters at a hypothetical level with each individual attempting to figure out how goals can possibly be achieved. Thus, for example, the Prophet has detailed specific acts that one has the right to expect from one’s brother and which one should also perform towards one’s brother. Thus, among those common obligatory acts of courtesy are the six mentioned by the Prophet:
“Six are the rights of a Muslim over another Muslim.... When you meet him, offer him greetings; when he invites you to a feast, accept it; when he seeks your sincere counsel, give it to him; when he sneezes and says, ‘al-hamdulillah,’ say, ‘May God show mercy to you’; when he falls ill, visit him; and when he dies, follow his funeral bier.” (Saheeh Muslim)
Beyond these six well-known practices, Islamic Law guides Muslims to many other practices that help gender love and closeness between the believers, which is an obvious goal of the Law itself. Thus, for example, if a Muslim loves another Muslim for the sake of God, he should inform the other individual of that feeling. The Prophet explained the reason for doing so when he said:
“If one of you loves his brother for the sake of God, he should inform of that as this will make the bond longer lasting and the love more confirmed.”
The Prophet also said:
“By the One in whose hand is my soul, you will not enter Paradise until you believe. And you do not believe until you love one another. Certainly, let me inform you of that which will establish such for you: spreading peace among yourselves.” (Saheeh Muslim)
This hadith could mean the spreading of the greetings of peace or doing actual deeds that bring about peace and togetherness.
The Prophet also noted the importance of giving gifts to one another. He said:
“Exchange gifts and you will love one another.” (As-Suyooti)
The Prophet also encouraged Muslims to visit one another. He stated:
“Visit one another occasionally and love [between you] will increase.” (al-Tabaraani)
In addition to all of these positive acts, when one avoids the forbidden acts, the results will also be positive for interpersonal relationships. In other words, when one avoids backbiting, slandering, lying, cheating, spying and so forth, nothing but good will result from the avoidance of these evil practices that Islam has clearly forbidden.
Thus, one can conclude that social cohesion among Muslims is definitely one of the most sought after goals in Islam. In addition, practical steps are laid down to ensure that this goal will be met.
 Recorded by ibn Abi Dunya in Kitaab al-Ikhwaan.