Upon encountering an enemy or those of authority

O Allah, we ask You to restrain them by their necks, and we seek refuge in You from their evil.

Reference:Abu Dawud 2/89, and Al-Hakim graded it authentic and Ath-Thahabi agreed 2/142.Hisnul Muslim 126

اللّهُـمَّ إِنا نَجْـعَلُكَ في نُحـورِهِـم وَنَعـوذُ بِكَ مِنْ شُرورِهـمْ

Transliteration

Allāhumma innā naj`aluka fī nuḥūrihimwa na`ūdhu bika min shurūrihim.

Translation

O Allah, we ask You to restrain them by their necks, and we seek refuge in You from their evil.