Harmalah bin Abd al-Aziz bin al-Rabi' bin Sabrah said: My uncle narrated to me from his father, from his grandfather, Sayyiduna Sabrah (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said: "Each of you must take care to have a sutrah (screen) for his prayer, even if it is only an arrow."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3464