Reference: Sharh ‘Umdatil-Fiqh – Tape No.4, Question No.30
Question: If a garment is soiled with an impurity, and I do not know exactly where, am I obliged to completely wash the garment?
Response: Yes, if you do not know whether [it is soiled] at the top, the middle or the bottom, nor at the front or back, then you should completely wash the garment so you can be certain it is entirely clean for sure. And the scholars have said if the area where the impurity has soiled the garment is unknown, then completely wash it so you can be certain [it is entirely clean].
