What should a person do who has masturbated and wiped the seminal fluid on the prayer rug, cannot wash it, and does not know the exact location of the seminal fluid?

"Madhī" (pre-seminal fluid) is impure, and anything it touches must be purified by pouring water over the affected area. If its location on the prayer rug is unknown, the entire rug must be washed if one intends to pray on it. As for the fluid that typically exits after masturbation, it is "manī" (semen), which, according to the soundest opinion, is pure. Therefore, the prayer rug does not need to be purified if it is touched by it.