Is it permissible to acquire knowledge from one who does not adhere to some of the obligatory Sunnahs (practices/traditions) reported from the Prophet (peace be upon him), such as growing a beard and not letting one's garment hang below the ankles?

A Muslim must follow the Prophet, peace and blessings be upon him, and no one else, for a person will be questioned about their adherence to the Messengers. It is not permissible to cling to anyone's action if it contradicts the Prophet, peace and blessings be upon him. A preacher must be a good example.

Regarding the issue of Isbal (letting garments hang below the ankles), scholars have differed. The majority of scholars hold that it is not forbidden unless it is done out of pride, while others consider it absolutely forbidden. The difference of opinion in this matter is permissible, and there should be no denunciation of those who hold differing views.

As for shaving or trimming the beard, the majority of scholars are of the opinion that growing it is obligatory, while a few consider shaving it makruh (disliked) but not haram (forbidden). These issues should not be a cause for slandering individuals or accusing them of violating the Sunnah, because they may admit of interpretation or excuse. They should not be a basis for judging people or a cause for dispute and division.

Discussion and advice on these issues are required, but there should be no exaggeration in them, making them matters of wala' and bara' (loyalty and disavowal), or preoccupation with them over what is more important in religion. It is not correct to abandon congregational prayer behind someone who is in this state, or to refrain from benefiting from their knowledge, especially in Western countries where preachers are few and greatly needed. May Allah have mercy on Al-Dhahabi, who said: "If every person who erred in his ijtihad – while having sound faith and striving to follow the truth – were to be abandoned and declared an innovator by us, then few of the Imams would remain safe with us."