Short answer
Yes. Cutting off a fellow Muslim and refusing to speak to them for more than three days over a personal quarrel is haram. The better of the two is the one who greets first. Avoiding someone to protect your religion or safety, such as an abuser or someone who leads you to sin, is allowed.
Deliberately cutting off a Muslim for more than three days for a worldly reason is haram. The minimum that ends it is giving and returning salam. Avoiding a person to escape harm or sin, or briefly as a correction, is permitted.
The four schools agree on this.
Explanation
The Prophet ﷺ said: it is not lawful for a man to cut off his brother for more than three nights, the two meeting and each turning away from the other. The better of them is the one who starts with salam. Three days gives time for anger to cool. After that, silence turns into a sin.
With relatives it is even more serious. He said that the one who cuts off family ties will not enter Paradise. Siblings who have not spoken for years over an inheritance, or cousins who ignore each other at weddings, need to repair this.
What ends the cutting off? At the least, greeting and returning salam. You do not have to become close friends again, but you must not keep up a cold war.
When keeping distance is allowed:
- a person who harms you, abuses you or puts you in danger;
- a friend who keeps pulling you into sin, such as drugs or haram relationships;
- a short boycott meant to correct someone, as when the Prophet ﷺ had the Companions avoid three men who stayed behind from Tabuk, until Allah accepted their repentance.
Blocking someone online to protect yourself is fine. Using silence to punish someone, the 'silent treatment' in families and marriages, is the kind the hadith forbids when it goes beyond three days. If you are the one cut off, keep saying salam; the sin is on the one who refuses. See also choosing friends.
The evidence
Quran, Surah Al-Hujuraat 49:10
إِنَّمَا ٱلْمُؤْمِنُونَ إِخْوَةٌۭ فَأَصْلِحُوا۟ بَيْنَ أَخَوَيْكُمْ ۚ وَٱتَّقُوا۟ ٱللَّهَ لَعَلَّكُمْ تُرْحَمُونَ ﴿١٠﴾
The believers are but brothers, so make settlement between your brothers. And fear Allah that you may receive mercy.
Believers must repair broken relations.
Sahih al-Bukhari 6077
Sahih... لا يحل لرجل أن يهجر أخاه فوق ثلاث ليال ...
"It is not lawful for a man to cut off his brother for more than three nights."
Cutting off a Muslim beyond three days is forbidden.
Sahih al-Bukhari 6077
Sahih... وخيرهما الذي يبدأ بالسلام ...
"The better of the two is the one who starts with salam."
Salam ends the cutting off.
Sahih al-Bukhari 5984
Sahih... لا يدخل الجنة قاطع ...
"The one who cuts off ties will not enter Paradise."
Cutting family ties is a major sin.
Where the ruling is recorded
- Fath al-Bari (Ibn Hajar), Kitab al-Adab, chapter on cutting off (al-hijra). Explains that salam ends the sin and when avoidance is allowed for religious reasons.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.