Invocation
After the last tashahhud and before salam
اللّهُـمَّ إِنِّـي ظَلَـمْتُ نَفْسـي ظُلْمـاً كَثـيراً وَلا يَغْـفِرُ الذُّنـوبَ إِلاّ أَنْت، فَاغْـفِر لي مَغْـفِرَةً مِنْ عِنْـدِك وَارْحَمْـني، إِنَّكَ أَنْتَ الغَـفورُ الرَّحـيم
O Allah, I have greatly wronged myself, and no one forgives sins but You. So, grant me forgiveness and have mercy on me. Surely, you are Forgiving, Merciful.
Al-Bukhari 8/168, Muslim 4/2078.