Sayyiduna Abu Dharr (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "When any one of you stands for prayer, if there is something in front of him equal to the back part of a camel's saddle, then that will serve as a sutrah (barrier) for him." Then the rest of the hadith was narrated. Bishr bin Mufaddal says that Yunus narrated to us a report exactly like the aforementioned hadith.