For one afraid of the ruler's injustice

اللَّهُمَّ ربَّ السَّمَوَاتِ السَّبْعِ، وَرَبَّ الْعَرْشِ الْعَظِيمِ، كُنْ لِي جَاراً مِنْ فُلاَنِ بْنِ فُلاَنٍ، وَأَحْزَابِهِ مِنْ خَلاَئِقِكَ، أَنْ يَفْرُطَ عَلَيَّ أَحَدٌ مِنْهُمْ أَوْ يَطْغَى، عَزَّ جَارُكَ، وَجَلَّ ثَنَاؤُكَ، وَلاَ إِلَهَ إِلاَّ أَنْتَ

O Allah, Lord of the seven heavens, Lord of the Magnificent Throne, be for me a support against [such and such a person] and his helpers from among your creatures, lest any of them abuse me or do me wrong. Mighty is Your patronage, and glorious are Your praises. There is none worthy of worship but You.

Al-Bukhari, Al-'Adab Al-Mufrad (no. 707). Al-Albani graded it authentic in Sahih Al-'Adab Al-Mufrad (no. 545).

الله أكبر، الله أعز من خلقه جميعاً ، الله أعز مما أخاف وأحذر ، أعوذ بالله الذي لا إله إلا هو ، الممسك السموات السبع أن يقعن على الأرض إلا بإذنه ، من شر عبدك فلان ، وجنوده وأتباعه وأشياعه ، من الجن والأنس ، اللهم كن لي جاراً من شرهم ، جل ثناؤك وعز جارك ، وتبارك اسمك ، ولا إله غيرك (ثلاث مرات)

Allah is the Most Great, Mightier than all His creation. He is Mightier than what I fear and dread. I seek refuge in Allah, Who there is none worthy of worship but Him. He is the One Who holds the seven heavens from falling upon the earth except by His command. [I seek refuge in You Allah] from the evil of Your slave [name of the person], and his helpers, his followers, and his supporters from among the jinn and mankind. O Allah, be my support against their evil. Glorious are Your praises and mighty is Your patronage. Blessed is Your Name, there is no true God but You. (Recite three times in Arabic.)

Al-Bukhari, 5/172.