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." (Using translation from Abū Dāʾūd 1537)
أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا خَافَ مِنْ رَجُلٍ أَوْ مِنْ قَوْمٍ قَالَ اللهُمَّ إِنِّي أَجْعَلُكَ فِي نُحُورِهِمْ وَأَعُوذُ بِكَ مِنْ شُرُورِهِمْ