There are five prerequisites for prayer. Each prerequisite must be met before a prayer is begun, and it must continue to be met throughout the performance of prayer. The absence of a single prerequisite prevents a prayer from being valid.
The first prerequisite is the absence of ritual impurity [ḥadath] and inexcusable filth. These were covered in sections 1.5.5, 1.6.1, and 1.9.1.
The second prerequisite is covering one’s nakedness with clothes that are pure. In this chapter, “nakedness” refers to that which Sacred Law requires one to cover in a particular context. During prayer, a man’s nakedness is the area between his navel and his knees. A woman’s nakedness during prayer is her entire body, excluding her face and hands up to the wrist. Her nakedness includes the underside of her jaw and the area behind her chin. Nakedness must be covered for prayer, even when alone in a locked and dark, windowless room.
For a garment to cover one’s nakedness, the material must be thick enough to hide the color of the underlying skin and hair. During prayer, it is not a requirement that the shape of the body also is covered. While it is not required that the clothing be baggy, and it is valid to pray in clothing that clings to the body and reveals its shape, it is offensive to do so.
The third prerequisite is praying on something that is pure. This includes the areas where the feet come into contact with the ground, and where the hands and knees and forehead come into contact when making prostration.
The fourth is knowing that the prayer time has entered. This is known by seeing that the time has entered (which was discussed in 2.1), or hearing that it has from someone you consider trustworthy.
The fifth is facing the direction of prayer. People who can see the Kaʿbah itself must face it. People who cannot see it must face its direction. Its direction is the shortest distance between them and the Kaʿbah. What direction would someone come from if they had walked in a straight line from the Kaʿbah to you? That’s the direction you need to face.
Sometimes it can be very difficult to face the direction of prayer, so in two situations it is permissible to deviate from the direction of prayer. The first is if there is intense fear or peril, such as in the middle of a battle or running away from a flood or tyrant. The second is if praying non-obligatory prayers during a journey while riding an animal or vehicle, like a horse, camel, ship, or train.