Prayer callus

A prayer callus, prayer bump, zabiba or zebiba () is a callus on the forehead caused by repeated ritual prostration, usually in Islamic prayer. Owing to its cultural signal of piety, it is also known as the "devout sign".

Islam requires its adherents to pray five times a day (known as salat), which involves kneeling on a prayer mat and touching the ground (or a raised piece of clay called turbah by the Shia) with one's forehead. When done firmly for extended periods of time, a callus – the "prayer bump" – can develop on the forehead which may be considered as a sign of piety and dedication. Some Muslims believe that It is referred to in the Quran as:

Some Muslims also believe that on the Day of Resurrection, this callus will fluoresce with an immense white light. With the growing popularity of the zabiba in Egypt, its visibility can enhance societal standing and reflect an individual's commitment to prayer, creating a favorable first impression. In some cases, the callus can be thick enough to create a noticeable bump that protrudes from the forehead.