Sayyiduna Talhah bin Ubaydullah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "When one of you places in front of himself something equal to the back-rest of a camel saddle, then no one's passing will harm him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3455