Ruling 136

There is no problem in selling or lending an impure thing that can be made pure. However, it is necessary to tell the other party about the thing being impure on two conditions:

1. The other party is at risk of opposing a legal responsibility; for example, he will use the impure thing in his food or drink, or it will invalidate the wuḍūʾ or ghusl with which he will perform an obligatory prayer. However, if this is not the case, it is not necessary to inform him; for example, it is not necessary to inform him about impure clothing with which he performs prayers because wearing pure clothing is not an absolute condition (al‐sharṭ al‐wāqiʿī)¹⁷ for the prayer to be valid;
2. One deems it probable that the other party will heed what he says. Therefore, if one knows that what he says will have no effect, it is not necessary to tell him.

¹⁷ An absolute condition is one that must be fulfilled for an action to be valid irrespective of the performer’s state of knowledge with regard to that condition. For example, performing rukūʿ in prayers is an absolute condition for the prayer to be valid because even if a person omits it unknowingly and realises this afterwards, his prayer is void and he must repeat it. However, wearing pure clothing in prayers is not an absolute condition because if one performs prayers with impure clothing and realises this afterwards, his prayer is deemed to be valid.