Question
If someone’s pure clothes mixed with their impure clothes and they prayed in one of the two, being cautious about the impurity of one of them, then they wanted to pray another prayer and their caution fell on the one they did not pray in?
Answer
I say, and with God's help: It is not correct; because the endorsement of ijtihad (juridical reasoning) is not invalidated by a similar ijtihad except in the case of the qibla (direction of prayer); because it can be subject to a change in direction through ijtihad, as it is a religious matter, while impurity is a tangible matter that cannot be made pure through ijtihad due to the necessity of repeating the prayer when impurity appears after ijtihad in clothing and utensils. Therefore, whenever we consider a garment pure through ijtihad out of necessity, it is not permissible to consider it impure through a similar ijtihad, as this would invalidate every prayer performed with what was initially considered impure, while it would be valid with what was considered pure. See: Maraqi al-Falah, pp. 34-35, and God knows best.