Fortification of the Muslims through remembrance and supplication from the Quran and the Sunnah Supplications
أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ وَأَشْهَدُ أَنَّ مُحَمَّدَاً عَبْدَهُ وَرَسُولَهُ
"I testify that there is no one worthy of worship besides Allah. He is all by Himself and has no partner and I testify that Muhammad is Allah's Rasul (Messenger)".
Eight doors of Jannah will be open for the reciter of this dua. He will be able to enter from whichever door he pleases. (Mishkat)
It is recorded in the same narration that the dua should be recited three times. (Hisnul Hasin)
Thereafter this dua should be recited
اللَّهُمَّ اجْعَلْنِي مِنَ التَّوَّابِينَ وَاجْعَلْنِي مِنَ الْمُتَطَهِّرِينَ
"O Allah, count me (make me) among those who seek forgiveness and amongst those who stay clean". (Hisnul Hasin)
Also recite this dua
سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا أَنْتَ أَسْتَغْفِرُكَ وَأَتُوبَ إِلَيْكَ
"O Allah, You are pure, I praise You and testify that only You are worthy of worship and I seek forgiveness from You (I turn to You for forgiveness). (Hisnul Hasin, from Mustadrak)