with him. For example: two men enter the mosque and find the first row complete, so they stand behind the row. One of them is in a state of ritual impurity and knows of his own impurity, while the other is in a state of purification and does not know that his companion is in a state of ritual impurity. According to the author’s statement, the prayer is invalid.

The reason is that this person standing there knows that he is in a state of ritual impurity, that his prayer is invalid, and that his companion has stood beside someone whose prayer is invalid; thus, he is standing alone.

However, the correct view in this matter is that the prayer of the second person—the one who is not in a state of ritual impurity—is valid if he does not know of his companion’s impurity, because he is excused on account of ignorance. He does not know that his companion is in a state of ritual impurity. But if he knows that his companion is in such a state, then he is standing alone, because he believes that he has prayed alongside someone whose prayer is invalid.

If he and his companion are both unaware until the prayer has ended, then the prayer of the one standing with the person in a state of ritual impurity is valid, because neither of them knew of the ritual impurity.

If someone were to ask: How could he not know?

The answer is that one of them may have eaten camel meat without knowing that it was camel meat, and then prayed. When the prayer had ended, he was informed that it had been camel meat. Thus, he had prayed while in a state of ritual impurity without knowing of his own impurity. His prayer is invalid, whereas the prayer of the one standing with him is valid.

The possible cases are as follows:

1. If both of them know of the ritual impurity, then both of their prayers are invalid. As for the one who is in a state of ritual impurity, this is obvious. As for the one who is not in such a state, it is because he stood with someone whom he knew to have an invalid prayer; thus, he is standing alone.