Dua--When encountering an enemy or being afraid of somebody, e.g. a ruler or your boss at work

1. It is also reported from Ibn ‘Umar that the Prophet, peace be upon him, said, “When you are afraid of a ruler or someone else, you should say, ‘There is no god but Allah, the Forbearing, the Gracious. Glory be to Allah, my Lord, glory be to Allah, the Lord of the seven heavens and of the mighty throne. There is no god but You, strong is your protection, and great is Your praise’.”

Source: Fiqh-us-Sunnah, Volume 4, #130

2. Ibn ‘Abbas said, “Hasbuna-Allah wa ni’am alwakil (Allah suffices us for everything and He is the most excellent guardian),” and then he added, “These words were uttered by the Prophet Ibrahim, peace be upon him, when he was thrown into the fire, and the Prophet Muhammad, peace be upon him, said these words when the people informed him, ‘The people have gathered against you’.” (Bukhari)

Source: Fiqh-us-Sunnah, Volume 4, #130

3. ‘Awf b. Malik reported that the Prophet, peace be upon him, judged the case of two men. The one who lost the case, turning away to go, said, “Allah is sufficient for us, and He is the best guardian.” The Prophet, peace be upon him, said to him, “Allah disapproves of weakness and impotence. You must put in effort and work, but if you are overwhelmed by a difficulty then say, ‘Allah is sufficient for me, and he is the most excellent guardian’.”

Source: Fiqh-us-Sunnah, Volume 4, #130