Thanks for your post. I’ve never noticed the prayer bruising. Love to learn new things about my enemy.
It's called a zebibah:
also known as a zabiba or zebiba, is a mark on the forehead of some Muslims, apparently due to the friction generated by repeated contact of the forehead with the prayer mat during daily prayers.It's something to be aware of. A beard can be shaved off. The "prayer bump" lasts a while. If you see somebody with one acting suspiciously, be alert.
Islam requires its adherents to pray five times a day (known as salat), which involves kneeling on a prayer mat and touching the ground with one's forehead. When done vigorously for extended periods of time, a prayer bump may develop. Some Muslims may consider the presence of a prayer bump to be a sign of religious dedication and piety.[1] Some Muslims also believe that on the day of judgment, this bump will particularly fluoresce an immense white light.[2] The bump also serves as a public demonstration of one's piety.
In extreme cases, the callus can be thick enough to create a real bump that protrudes from the forehead. They may also develop due to frequent prayer on hard surfaces such as stone floors.