Caused by extended pressure.
Pressure ulcers, also known as bedsores, are localized damage to the skin and/or underlying tissue that usually occur over a bony prominence as a result of usually long-term pressure, or pressure in combination with shear or friction. The most common sites are the skin overlying the sacrum, coccyx, heels, and hips, though other sites can be affected, such as the elbows, knees, ankles, back of shoulders, or the back of the cranium...
Although often prevented and treatable if detected early, pressure ulcers can be very difficult to prevent in critically ill people, frail elders and individuals with impaired mobility such as wheelchair users (especially where spinal injury is involved). Primary prevention is to redistribute pressure by regularly turning the person. The benefit of turning to avoid further sores is well documented since at least the 19th century.
Wikipedia, Pressure Ulcer, 2019
Primary prevention is to redistribute pressure by regularly turning the person. However this was portrayed in the Quran 1400 years before it was discovered.
[Quran 18:18] You would think them awake, although they were asleep. And We turned them over to the right, and to the left, with their dog stretching its paws across the threshold. Had you looked at them, you would have turned away from them in flight, and been filled with fear of them.
"And We turned them over to the right, and to the left" today we know why; in order to prevent bedsores.
How could an illiterate man who lived 1400 years ago have known how to prevent bedsores?