Is it obligatory to wash semen if it gets on the bed, and does that affect the validity of the prayer of a grandmother who prays sitting on the bed?

The preponderant opinion is that semen is pure, and therefore, it is not obligatory to wash it, nor does prayer become invalid in a place it has touched. However, it is preferable to wash and remove it because it is considered repulsive, and to avoid the difference of opinion of those who consider it impure.