At the end of the prayer say three times:
Astaghfirullahu-l-Adheem, la ilaha ila Hu, al Hayy ul Qayyum wa atubu ilaih.
(I ask God for forgiveness and there is no God but He the Living, the Everlasting, and to Him I turn in repentance.)
Allahumma anta-s-salam wa minka-s-salam wa ilaika yauda salam tabarakta rabbana wa ta `alaita ya dhul jalali wal ikram.
(O Allah You are the Peace and from You comes the Peace. Give us the Peace. Blessed art Thou the most High. O Lord of majesty and bounty.)
La ilaha illa Allah wahda hu la sharik Allah Lahul mulk wa lahul hamd Yuhyi wa yumitu wa huwa ala kulli shay'in qadir.
(There is no God but Allah He is the One and there is no partner for Him To Him is all the World and to Him all the Praise He gives life and He takes life and He is powerful over everything.)
Then say thirty three times each:
Allahu la ilaha illa Huwa, Al-Haiyul-Qaiyum
La ta'khudhuhu sinatun wa la nawm,
lahu ma fis-samawati wa ma fil-'ard
Man dhal-ladhi yashfa'u 'indahu illa bi-idhnihi
Ya'lamu ma baina aidihim wa ma khalfahum,
wa la yuhituna bi shai'im-min 'ilmihi illa bima sha'a
Wasi'a kursiyuhus-samawati wal ard,
wa la ya'uduhu hifdhuhuma Wa Huwal 'Aliyul-Adheem
In the Name of Allâh, the Most Gracious, the Most Merciful.
"Allah! There is no god but He - the Living, The Self-subsisting, Eternal. No slumber can seize Him Nor Sleep. His are all things In the heavens and on earth. Who is there can intercede In His presence except As he permitteth? He knoweth What (appeareth to His creatures As) Before or After or Behind them. Nor shall they compass Aught of his knowledge Except as He willeth. His throne doth extend Over the heavens And on earth, and He feeleth No fatigue in guarding And preserving them, For He is the Most High. The Supreme (in glory)."
(This Verse 2:255 is called Ayat al-Kursi)