Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates marfu‘an that the Prophet (peace and blessings be upon him) said: "When any one of you prays, he should pray facing something which he takes as a sutrah. If he does not find anything, he should draw a line. Then, whoever passes in front of him after that will not harm him."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصلوٰة / 158
Hadith Takhrij«سنن ابوداود ، كتاب الصلاة ، باب الخط اذالم يجد عصا ، رقم : 689 . قال الشيخ الالباني ، ضعيف . سنن ابن ماجه ، رقم : 943 . مسند احمد : 254/2 .»