Riyad Us-Saliheen (Gardens of the Righteous)

Chapter 173
Supplication if one Fears (Harm)

981. Abu Musa Al-Ashari (May Allah be pleased with him) reported: When the Messenger of Allah (PBUH), feared mischief from a people, he would supplicate: "Allahumma inna naj`aluka fi nuhurihim, wa na`udhu bika min shururihim (O Allah! We ask You to face them, and seek Your Protection against their evil.''
[Abu Dawud and An-Nasa'i].

Commentary:  Allah's Help, we are told, is a protection against all perils. Through this prayer we seek His Help with the conviction that the deceptions and designs of the infidels will turn back upon them.