What is the ruling on prayers that were performed with a garment afflicted by impurity, based on the opinion that removing impurity from the garment is not obligatory, and did the Prophet, may Allah bless him and grant him peace, persist in reciting the Qunut in the Fajr prayer until he departed from this world?

Among the conditions for the validity of prayer is purification from impurity on one's clothes, body, and place. So, whoever prays in clothes that have impurity, knowing about it and being able to remove it, their prayer is invalid and must be repeated. As for impurity that is difficult to guard against, it is excused. The hadith (definition), "The Messenger of Allah (peace be upon him) continued to perform Qunut in Fajr until he departed from this world," was narrated by Ahmad from Anas, and its chain of transmission is weak.