Abu Burdah bin Abdullah bin Qays (may Allah have mercy on him) says that his father (may Allah be pleased with him) narrated that whenever the Prophet (peace and blessings be upon him) feared a people, he would say: 'Allahumma inna naj'aluka fi nuhurihim wa na'udhu bika min shururihim' (O Allah, we place You against them, and we seek refuge in You from their evils.)
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10325