The Effect of Prostration

Imam Ali (AS) said, 'I hate it for a man to have a smooth forehead not having any trace of prostration on it.

Imam al-Baqir (AS) said, 'My father (AS) used to have protruding marks from prostration on his forehead, which he used to cut twice a year, and every time he would do so, he would scrape off five calluses, and came to be nicknamed 'the one with calluses.