Is covering the 'awrah (intimate parts) a prerequisite for the validity of the prayer?
Chapter on the Description of Prayer
Al-Mughni
Book of Prayer
Primary text
Covering the 'awrah from sight with something that does not reveal the skin is obligatory and a condition for the validity of the prayer. This is the position of Al-Shafi'i and the Ashab Al-Ra'y (Hanafi school). The evidence for this obligation is the Hadith of Aisha: The Prophet (peace be upon him) said, "Allah does not accept the prayer of a menstruating woman except with a khimar (head covering/veil)" and the Hadith of Salama bin Al-Akwa': when asked about praying in a single garment while hunting, the Prophet replied, "Yes, but tie it even with a thorn." Furthermore, there is a consensus, according to Ibn Abd al-Barr, that prayer is nullified if one capable of covering themselves prays naked.
Supporting text
Some scholars within the Maliki school hold that covering the 'awrah is obligatory but not a condition for validity. Others among them state it is a condition only when one remembers (Dhakir) and not when one forgets (Sahin). Their argument is that its obligation is not specific to prayer, so it cannot be a condition for prayer, analogous to avoiding prayer in a usurped dwelling.