What should I do when I find a slight or non-slight trace on my clothes after passing wind?

If a Muslim finds impurity on his clothes, and it is not a matter of obsessive whisperings (waswasah), he must wash the place of the impurity on the garment or body before prayer or any act of worship that requires ritual purity from defilement (khabath), because purity from impurity is a condition for the validity of prayer. However, if the impurity is slight and difficult to avoid, there is a difference of opinion regarding it. But if what he finds is merely obsessive whisperings, he must completely disregard them.