What is the ruling on one who mixed pure garments with impure ones and forgot which are pure and which are impure?

If pure clothes become mixed with impure ones, one should strive to distinguish the pure garments. If a sign appears to him indicating a pure garment, he should pray in it. If he cannot distinguish the pure from the impure, he should pray naked and repeat the prayer. According to the Hanbalis, he should pray the number of impure clothes plus one prayer. Sheikh Ibn Uthaymeen preferred exercising diligence (taharri); if he is reasonably certain about the purity of one of the garments, he should pray in it. If he can wash one of the garments to pray in it, he is obligated to do so.