If semen gets on part of the underpants, should that part be washed or the whole garment?

Question:
Honorable Shaykh, may Allah grant you success. He says: If semen gets on the underpants, is it sufficient to wash only the part that was affected, or is it necessary to wash the entire underpants?

Answer:
Semen is pure, and washing it is a matter of cleanliness, not of removing ritual impurity. If it is dry, it should be rubbed off; if it is wet, it should be washed for the sake of cleanliness. Even if you pray without having washed it, your prayer is valid. The Prophet (peace and blessings be upon him) used to pray while its trace was on him. Yes.