for a man to pray with both thighs exposed—whether or not one maintains that they form part of the ʿawrah—and he may not circumambulate the Kaʿbah naked. Rather, he is required to perform the prayer in at least one garment, and this is indispensable: if the cloth is narrow he girds it about his waist, and if it is wide he wraps it around himself. The same obligation holds if he were praying alone in his own house, for the scholars unanimously agree that he must still cover that area.
As for a man who prays with his thighs uncovered while he is able to wear a lower wrap, such a prayer is invalid¹, and there should be no disagreement about this. Those who rested the matter on the two reports about what constitutes ʿawrah, as some have done, have erred; neither Aḥmad nor anyone else ever said that a worshipper may pray in such a condition. How could that be, when Aḥmad commands him to cover his shoulders—so how could he permit him to expose his thighs? That settles the point.
Scholars have differed over whether covering the ʿawrah is obligatory when a man is alone, but they have not differed that during the prayer clothing is essential and that praying naked while one is able to dress is invalid by unanimous agreement. For this reason Aḥmad and others allowed those who possess no garments at all to pray seated, with their imam seated in their midst—unlike the ruling outside of prayer. This covering is mandated out of reverence for the prayer, not merely because of the gaze of onlookers.
The Prophet ﷺ said in the ḥadīth of Bahz ibn Ḥakīm, from his father, from his grandfather, when the latter asked, “O…"