According to Muslim scholars, brotherhood in Islam dictates purity of hearts and love towards one another (for Allah’s sake). If there should occur a dispute of some kind between fellows, each party should seek to tolerate and reconcile with the other party, bearing in mind that people’s deeds are presented before Almighty Allah and He Most High forgives every believing person except those who are on bad terms with one another. However, one may forsake one’s brother if the latter is committing a sin as a means of rebuking him for such a sin and trying to make him return to the right path.
Dr. Ahmad Ash-Sharbasi, professor of `aqeedah and philosophy at Al-Azhar University, stated: Allah Almighty says: (The believers are naught else than brothers) (Al-Hujurat 49: 10). Brotherhood in Islam requires that brethren have pure relations and are on good terms with one another. They are to love and treat one another kindly, governed in this respect by the bond of good Muslim brotherhood. The Prophet (peace and blessings be upon him) was reported to have said, “A believer to another believer is like a building whose different parts enforce each other.” This indicates how strong should be the relation of brotherhood in faith.

The Prophet (peace and blessings be upon him) was also reported to have said in a long hadith, “And nurse no aversion and hostility against one another” (Reported by Al-Bukhari and Muslim).
the Prophet (peace and blessings be upon him) also said, “Let not any one of you desert his brother more than three days. They meet and each of them turns away from the other; but the best of the two is the one who starts with the salutation of peace” (Reported by Al-Bukhari and Muslim).
he (peace and blessings be upon him) was also reported to have said, “The deeds of people are presented every week on two days, Monday and Thursday, and every believing servant is granted pardon except the one in whose (heart) there is rancor against his brother. It will be said to him (and the one with whom he disputes), ‘Leave them and put them off until they are turned to reconciliation’” (Reported by Muslim).
the Prophet (peace and blessings be upon him) also said, “The gates of Paradise are not opened but on two days, Monday and Thursday; then every servant (of Allah) is granted pardon who does not associate anything with Allah except the person in whose (heart) there is rancor against his brother. And it will be said thrice, ‘Look towards both of them until there is reconciliation’” (Reported by Muslim).

Of the hadiths reported also in this regard are the Prophet’s words “It is not permissible for a Muslim to desert his brother for more than three days; if he does so and dies (before he reconciles with his brother), he will enter the Hellfire.” Mind that what the Prophet (peace and blessings be upon him) meant in this hadith was referring to one who disputes with his brother without strong reason and dies before he repents from this fault. Another hadith reported in the same context goes “He who deserts his brother for a year is as if he had shed his blood.” According to scholars, these two hadiths are reported to intimidate Muslims to shun disputes and to plant in them aversion towards being on bad terms with one another.
Based on this, jurists say that it is not permissible for a Muslim to forsake his brother in faith for more than three days. If a desertion of this kind occurs between two Muslims, one of them should seek to meet the other and greet him (as a gesture of reconciling with him); if the other returns the greeting, both will be rewarded by Almighty Allah, though the former, having taken the initiative of reconciliation, will be better in Allah’s sight. If the latter disregards the greeting of the former (indicating disinclination to reconciling with him), he will incur the sin upon himself and the former will not be questioned, for he has redeemed the mistake he has committed by seeking reconciliation.
to sum up, a Muslim is not permitted to break with his brother for more than three days. But he may do so only in one case: when his brother is disobeying Almighty Allah and His Messenger. Such a desertion may spare one being influenced by the sinner or may motivate the sinner to return to the right path. It is only in a case like this that one may break with one’s brother in Islam.
May Allah support the believers who keep the bond of brotherhood in faith and help one another in obeying Almighty Allah.