Shaykh Al-Fawzaan said, “Boycotting (al-hajr) is to stop talking to someone, to stop sitting with them and giving them salaam.
Boycotting a believer is not allowed for more than three days if it is about something worldly, in fact he should reconcile with his brother and give him salaam when he meets him.
To begin with, he (a Muslim) shouldn’t (even) boycott (another Muslim) over a worldly matter, but if it does take place then it should not be for more than three days, this is what the hadith, ‘It is not allowed for a Muslim to boycott his brother for more than three days,’ means, i.e., when the ostracising (boycotting) is over a worldly issue.
As for when it is over a sin [a sin here also includes a bidah (innovation) which is less than kufr] which the person being boycotted has committed, a major sin which he has not left, then he must be advised and directed to fear Allah the Mighty and Majestic.
If he does not desist from that sin and does not repent, then he is boycotted, because the boycotting acts as a reprimand and deterrent for him, maybe he will repent [because of it].
Unless ostracising (boycotting) him is something which will lead to harm, whereby it is feared that he will increase sinning and that it will result in greater evil then in such a situation it is not allowed to boycott him, boycotting a sinner is only allowed if there is benefit to it and if it doesn’t lead to greater harm.
And success lies with Allah.”
Ref: Al-Muntaqaa min Fataawaa Fadeelatis, Shaikh Saalih ibn Fawzaan ibn ’Abdillaah al-Fawzaan, vol. 1, pp. 397-398 via GiftsofKnowledge.net
Posted by Abdul Kareem Ibn Ozzie