Rules concerning use of lavatory
Urination and Excretion
57. It is obligatory to conceal one's private parts in the toilet and at all times from adult persons (Mukallaf) even if they are one's nearest relatives like mother and sister, similarly, it is obligatory to conceal one's private parts from insane persons, and from children who can discern between good and evil. However, husband and wife are exempted from this obligation.