prayer callus prayer callus a prayer callus, zabiba or zebiba (arabic: زبيبة zabība, "raisin") is a callus on the forehead present in some devout praying muslims, mainly in egypt. owing to its societal significance it is also known as the "devout sign". among notable egyptian leaders anwar sadat's reputation for personal piety was evidenced by a callus on his forehead from repeated prostration in prayer. a pilgrim with prayer bump photographed outside masjid al-haram. 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. it is mentioned in the quran as: muḥammad is the messenger of allah; and those with him are forceful against the disbelievers, merciful among themselves. you see them bowing and prostrating , seeking bounty from allah and pleasure. their sign is in their faces from the effect of prostration . that is their description in the torah. and their description in the gospel is as a plant which produces its offshoots and strengthens them so they grow firm and stand upon their stalks delighting the sowers – so that he may enrage by them the disbelievers. allah has promised those who believe and do righteous deeds among them forgiveness and a great reward some muslims also believe that on the day of resurrection, this callus will fluoresce with an immense white light. however, riya (showing-off) is prohibited in islam; if the prayer bump may result in riya, it is recommended to take precautionary measures to stop a bump forming, as worship may be deemed void due to riya. in extreme cases, the callus can be thick enough to create a noticeable bump that protrudes from the forehead.