The main purpose of a sutrah is to warn people not to pass in front of someone who is praying. If a person spreads a prayer mat with this intention, so that no one passes in front of him within the sutrah area, then such a mat or chatai, which is about two and a half to three arms in length, fulfills the purpose of a sutrah. In this case, it is enough to be considered a sutrah, and passing in front of it is forbidden.
However, the mats and carpets that are normally spread in mosques, or the space kept between two mats or two rows, do not serve as a sutrah. This is because a sutrah is meant to alert the passerby, and since these mats are always spread, the purpose of a sutrah is not achieved. This is the Islamic ruling explained by Islamic scholars in their fatwa.
