Is a prayer valid when there is doubt about the purity of clothes due to humidity, or must it be repeated upon returning home, and is this doubt a form of Waswas (obsessive whispering)?

Underwear that has become impure must be changed or purified before prayer, because purification is one of the conditions for the validity of prayer. When going out, one can take underwear that can be purified or removed at the time of prayer if the impurity is not continuous. However, if it is continuous, refer to Fatwa (definition) no. 35854. Prayers performed with knowledge of an impurity that could be removed or the garment changed must be re-offered. However, if it was not possible, re-offering is not obligatory. It is advised not to succumb to obsessive doubts (waswas).