حَدَّثَنَا عِيسَى بْنُ حَمَّادٍ الْمِصْرِيُّ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَخِيهِ، عَبَّادِ بْنِ أَبِي سَعِيدٍ أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ، يَقُولُ كَانَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ يَقُولُ ‏"‏ اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنَ الأَرْبَعِ مِنْ عِلْمٍ لاَ يَنْفَعُ وَمِنْ قَلْبٍ لاَ يَخْشَعُ وَمِنْ نَفْسٍ لاَ تَشْبَعُ وَمِنْ دُعَاءٍ لاَ يُسْمَعُ ‏"‏ ‏.‏

It was narrated from Abu Bakr Siddiq that

he said to the Messenger of Allah (saas): "Teach me a supplication which I can say during my prayer." He said: "Say: Allahumma inni zalamtu nafsi zulman kathiran wa la yaghfirudh-dhunub illa Anta, faghfirli maghfiratan min 'indika warhamni, innaka Antal-Ghafurur-Rahim (O Allah, I have wronged myself greatly and no one forgives sins but You, so grant me forgiveness from You and have mercy on me, for You are the Oft-Forgiving, Most Merciful)."