The second category:

When bathhouses are free of prohibited conduct, whether in cold or hot lands, there is no doubt that building them is not forbidden. Bathhouses were built in the Hijāz and Iraq during the time of the Companions, in the days of ‘Alī and others, and they approved of them.

Ahmad did not say that this was forbidden. Rather, he disapproved of it because bathhouses generally involve both permissible and prohibited activities. In the time of the Companions, people were too mindful of Allah and too observant of His limits for prohibited conduct to become widespread in them. Thus, bathhouses were not disapproved of at that time. Even if prohibited conduct occasionally occurred in them, this was comparable to its occurrence in marketplaces and houses whose construction was not prohibited, even though people could do without them.

The third category:

When bathhouses serve a need but generally involve prohibited conduct, as is the case with most bathhouses in cold lands: the inhabitants of those regions cannot do without bathhouses, yet these ordinarily cannot be free of prohibited conduct. Here too, no blanket disapproval of their construction and sale is warranted. This is because the Prophet’s words, may Allah bless him and grant him peace:

“The lawful is clear, and the unlawful is clear. Between them are doubtful matters which many people do not understand. Whoever avoids doubtful matters safeguards his honour and his religion, while whoever falls into doubtful matters falls into the unlawful, like a shepherd grazing his flock around a protected pasture, on the verge of straying into it.”

require only the avoidance of doubtful matters in which the lawful is difficult to distinguish from the unlawful, unlike