Amir bin Dhu'ayb says: It was said to Ibn Abbas (may Allah be pleased with him): Do you pray behind these (rulers) in the enclosure (maqsurah)? He said: "Yes; they fear that we would rip their bellies open."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5242