This is one of the ways in which Shaytaan causes division among Muslims, and those who follow in the footsteps of Shaytaan may forsake a Muslim brother for no legitimate reason, but because of a dispute over money or some trivial disagreement. This division may continue for a lifetime, with one swearing that he will never speak to the other and vowing never to set foot in his house, turning away if he sees him in the street and ignoring him if he happens to encounter him in a gathering, shaking hands with everyone else but him. This is a cause of weakness in the Muslim community, hence the ruling concerning this is decisive and the warning against it is stern. Abu Hurayrah (may Allaah be pleased with him) reported that the Prophet (peace and blessings of Allaah be upon him) said: "It is not permitted for a Muslim to forsake his brother for more than three (days); whoever does this and dies, he will enter Hell." (Reported by Abu Dawud, 5/215; see also Saheeh al-Jaami', 7635).
Abu Khuraash al-Aslami (may Allaah be pleased with him) reported that the Prophet (peace and blessings of Allaah be upon him) said: "Whoever forsakes his bother for a year, it is as if he has shed his blood." (Reported by al-Bukhaari in al-Adab al-Mufrad, hadeeth no. 406; see also Saheeh al-Jaami', 6557).
It is bad enough that division among Muslims results in their being deprived of the forgiveness of Allaah, may He be glorified. Abu Hurayrah reported that the Prophet (peace and blessings of Allaah be upon him) said: "The deeds of the people are shown to Allaah twice a week, on Mondays and Thursdays; He forgives all His believing slaves, except for the one between whom and his brother is enmity. He says, 'Leave these two until they reconcile.'" (Reported by Muslim, 4/1988).
Whichever of the two parties repents to Allaah must then go back to his brother and greet him with salaam; if he does this and the other person ignores him, then the former is free of blame and the responsibility falls upon the latter. Abu Ayyoob reported that the Prophet (peace and blessings of Allaah be upon him) said: "It is not permissible for a man to forsake his brother for more than three nights, each turning away if they meet. The better of the two is the one who is the first to greet the other with salaam." (Reported by al-Bukhaari, Fath al-Baari, 10/492).
There may be cases where there is a legitimate reason for forsaking a person, such as his not praying, or persisting in immorality. If forsaking him will benefit him by bringing him to his senses and making him see the error of his ways, then it is obligatory to forsake him, but if it will only make him more stubborn and persistent in his sin, then it is not right to forsake him, because nothing is achieved by doing so. Forsaking him will only make matters worse, so the right thing to do is to continue treating him kindly, and advising and reminding him.
In conclusion, this is what Allaah has enabled me to write about the prohibitions that are widely ignored. This is a lengthy topic, and in order that readers may further benefit, another chapter is needed, in which a group of prohibitions mentioned in the Qur'aan and Sunnah will be listed. This will appear as a separate work, in sha Allaah. I ask Allaah, may He be glorified and exalted, by His Most Beautiful Names, to give us enough awareness and fear of Him to keep us away from sin, and enough devotion and obedience to Him to help us reach His Paradise, to forgive us for our sins and by His grace to make us content with what He has permitted and keep us away from what He has forbidden. May He accept our repentance and cleanse us from sin, for He is the All-Hearing, the One Who answers prayers. May the peace and blessings of Allaah be upon the Unlettered Prophet, Muhammad, and upon all his family and companions. All praise be to Allaah, Lord of the Worlds.