that the Prophet, may Allah bless him and grant him peace, prayed in his sandals, then removed them during the prayer when Gabriel informed him that there was filth on them. He continued his prayer without starting it again, although the filth had been present at the beginning of the prayer, but he had not known about it. His taking the trouble to remove them during the prayer—although, had there been no need, doing so would have been pointless or disliked … (1)—indicates that avoiding impurity when aware of it is commanded, and provides grounds for concluding that it is excused when one is unaware of it.

Abū Dāwūd also narrated from Umm Jahdar al-ʿĀmiriyyah that she asked ʿĀ’ishah about menstrual blood getting onto clothing. She replied:

“I was with the Messenger of Allah, may Allah bless him and grant him peace, with our inner covering over us, and we had placed a cloak over it. In the morning, the Messenger of Allah, may Allah bless him and grant him peace, took the cloak, put it on, and went out to perform the dawn prayer. He then sat down, and a man said, ‘Messenger of Allah, here is a patch of blood.’ The Messenger of Allah, may Allah bless him and grant him peace, gathered the cloth around it and sent it to me, bundled up, with a boy, saying, ‘Wash this, dry it, and send it back to me.’ I called for my bowl, washed it, dried it, and returned it to him. The Messenger of Allah, may Allah bless him and grant him peace, came at midday wearing it.”

In this hadith, he did not instruct those who had prayed behind him to repeat the prayer, nor did he tell them that he would repeat it or that he was required to do so. Nor did ʿĀ’ishah mention any such thing. The apparent implication is that he did not repeat it. Another reason is that impurity falls under the category of things prohibited in prayer, and in matters involving prohibitions