According to the hadith of Abdullah ibn Abbas, the Prophet commanded that seven parts of the body must touch the ground in Sajdah and nothing like hair or cloth should block them. In another hadith, the Prophet told a man to make Sajdah and place his forehead directly on the ground.

Based on these texts, Islamic scholars state that keeping the forehead uncovered and touching the ground is obligatory. If any cloth connected to the body, such as a cap or scarf, or even falling hair comes between the forehead and the ground, then the Sajdah becomes invalid. And when Sajdah is invalid, the entire prayer becomes invalid.