Abdul Malik bin Aby عبد الملك بن أبي سليمان · Hot Baths (Kitab Al-Hammam)

The Prophet (ﷺ) said: After some time the lands of the non-Arabs will be conquered for you, and there you will find houses called hammamat (hot baths). so men should not enter them (to wash) except in lower garments, and forbid the women to enter them except a sick or one who is in a child-bed.

The Messenger of Allah (ﷺ) saw a man washing in a public place without a lower garment. So he mounted the pulpit, praised and extolled Allah and said: Allah is characterised by modesty and concealment. So when any of you washes, he should conceal himself.