Must outer garments be sprinkled with water if they come into contact with inner garments that have been soiled by mathi (pre-seminal fluid) or urine?

If impurity stains the inner garment, then if it is thick and the impurity does not transfer to what it touches, only the stained garment needs to be purified. However, if it is thin or the impurity is abundant such that it transfers to the outer garment, then the outer garment must also be purified. If one is not certain that the impurity reached the outer garment, the default is that it did not reach it, and therefore it does not need to be purified. Urine is purified by washing, whereas there is a difference of opinion regarding madhy (pre-seminal fluid): the Hanbalis hold that sprinkling suffices, while the Shafi'is hold that washing is required.