Is it permissible to place a chair in front of a worshipper to act as a sutrah during supererogatory prayers in the mosque, especially when there is no space available behind pillars and walls, and what if all worshippers were to do that?

Taking a Sutra (barrier) in front of the worshipper is established from the Prophet, peace and blessings be upon him. The majority of jurists interpreted the command as a recommendation, not an obligation, because he sometimes omitted the Sutra. Some scholars stated that the Sutra is obligatory if there is a fear of someone passing by, but in the desert, one has a choice. This excludes those who pray near the Kaaba. Some scholars have permitted drawing a line instead of a Sutra when one is unavailable, and some believe that the end of the prayer rug serves the purpose of a line.