Upon encountering an enemy or those of authority
اللّٰهُمَّ إِنَّا نَجْعَلُكَ فِيْ نُحُوْرِهِم، وَنَعُوْذُ بِكَ مِنْ شُرُوْرِهِمْ
O Allah, we ask You to restrain them by their necks and we seek refuge in You from their evil
اللّٰهُمَّ أَنْتَ عَضُدِي، وَأَنْتَ نَصِيْرِي، بِكَ أَحُوْلُ وَبِكَ أَصُوْلُ، وَبِكَ أُقَاتِلُ
O Allah, You are my strength and You are my support. For Your sake I go forth and for Your sake I advance and for Your sake I fight.
حَسْبُنَا اللّٰهُ وَنِعْمَ الْوَكِيْلُ
Allah is sufficient for us and the best of those on whom to depend.
Surah Al-Imran - 3:173
Dua against the oppression of rulers
اللّٰهُمَّ رَبَّ السَّمَوَاتِ السَّبْعِ، وَرَبَّ الْعَرْشِ الْعَظِيْمِ، كُنْ لِيْ جَاراً مِنْ فُلاَنِ بْنِ فُلاَنٍ، وَأَحْزَابِهِ مِنْ خَلاَئِقِكَ، أَنْ يَّفْرُطَ 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 (say the person's name) 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.
Dua against the oppression of rulers
Say three times:
اللّٰهُ أَكْبَرُ، اللّٰهُ أَعَزُّ مِنْ خَلْقِهِ جَمِيْعاً، اللّٰهُ أَعَزُّ مِمَّا أَخَافُ وَأَحْذَرُ، أَعُوْذُ بِاللّٰهِ الَّذِيْ لاَ إِلَهَ إِلاَّ هُوَ، الْمُمْسِكِ السَّمَوَاتِ السَّبْعِ أَنْ يَّقَعْنَ عَلَى الْأَرْضِ إِلاَّ بِإِذْنِهِ، مِنْ شَرِّ عَبْدِكَ فُلاَنٍ، وَجُنُوْدِهِ وَأَتْبَاعِهِ وَأَشْيَاعِهِ، مِنَ الْجِنِّ وَالإِنْسِ، اللّٰهُمَّ كُنْ لِيْ جَاراً مِنْ شَرِّهِمْ، جَلَّ ثَنَاؤُكَ وَعَزَّ جَارُكَ، وَتَبَارَكَ اسْمُكَ، وَلاَ إِلَهَ غَيْرُكَ
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 (say the person's name), 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.
Dua made against an enemy
اللّٰهُمَّ مُنْزِلَ الْكِتَابِ، سَرِيْعَ الْحِسَابِ، اهْزِمِ الأَحْزَابَ، اللّٰهُمَّ اهزِمْهُمْ وَزَلْزِلْهُمْ
Allah, Revealer of the Book, Swift to account, defeat the groups (of disbelievers). O Allah, defeat them and shake them.
What to say when in fear of people
اللّٰهُمَّ اكْفِنِيْهِمْ بِمَا شِئْتَ
O Allah, suffice (i.e. protect) me against them however You wish.