Is it obligatory to cover the face and to boycott a teenage brother who does not observe prayer, and is it permissible to incite the family not to eat or speak with him?

First: It is advisable to separate the bedrooms of brothers and sisters, especially during adolescence, to prevent the exposure of 'awrah (intimate parts) or the occurrence of temptation. This separation is particularly emphasized if the two individuals are solely a brother and a sister, or if their religious commitment is weak. If separation is not possible, there is no harm, provided that extra caution and vigilance are exercised, and parental supervision is maintained.

Second: Brothers and sisters must advise and be affectionate towards each other. If one finds their brother or sister not following guidance, they should advise them in the best manner and be patient with them, especially if they are young.

Third: If advice is unsuccessful, and it is believed that boycotting or withdrawing from them will rectify their situation, then there is no harm in doing so. However, if boycotting would increase their stubbornness or corruption, then it is not permissible. If it has no positive or negative effect, then the matter is left to the prevailing circumstances.