When the Prophet ﷺ feared a (group of) people, he would say: "O Allah, we make Thee our shield against them, and take refuge in Thee from their evils."  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا خَافَ قَوْمًا قَالَ اللَّهُمَّ إِنَّا نَجْعَلُكَ فِي نُحُورِهِمْ وَنَعُوذُ بِكَ مِنْ شُرُورِهِمْ