Does ritual impurity transfer to the hand if it touches a dry impure spot? And is it obligatory to clean the apartment floor if water from washing pillows, mixed with semen and prostatic fluid, drips onto it? And how can one distinguish ritually pure pillows from impure ones if they bear many yellow stains?

If semen mixes with madhi (pre-seminal fluid), then clothes and similar items are purified by sprinkling them with water. It is sufficient to sprinkle water on the area of impurity to consider it pure. As for the transfer of impurity from pillows contaminated with madhi to a wet hand, it does not transfer according to the opinion of many scholars. It is permissible for those afflicted with waswas (obsessive doubts) to adopt this view as a تسهيل (facilitation) for them. However, the opinion regarding the purity of madhi attributed to Imam Ahmad is weak and not to be relied upon.