It was narrated that Anas bin Malik said:

"A man come to the Prophet (saas) and said: 'O Messenger of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter.' Then (the man) came the next day and said: 'O Messenger of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter.' Then (the man) came the third day and said: 'O Prophet (ﷺ) of Allah, what supplication is best?' He said: 'Ask your Lord for forgiveness and to be kept safe and sound in this world and in the Hereafter, for if you are forgiven and kept safe and sound in this world and the Hereafter, you will have succeeded.'"

حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ إِبْرَاهِيمَ الدِّمَشْقِيُّ، حَدَّثَنَا ابْنُ أَبِي فُدَيْكٍ، أَخْبَرَنِي سَلَمَةُ بْنُ وَرْدَانَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ أَتَى النَّبِيَّ ـ صلى الله عليه وسلم ـ رَجُلٌ فَقَالَ يَا رَسُولَ اللَّهِ أَىُّ الدُّعَاءِ أَفْضَلُ قَالَ ‏"‏ سَلْ رَبَّكَ الْعَفْوَ وَالْعَافِيَةَ فِي الدُّنْيَا وَالآخِرَةِ ‏"‏ ‏.‏ ثُمَّ أَتَاهُ فِي الْيَوْمِ الثَّانِي فَقَالَ يَا رَسُولَ اللَّهِ أَىُّ الدُّعَاءِ أَفْضَلُ قَالَ ‏"‏ سَلْ رَبَّكَ الْعَفْوَ وَالْعَافِيَةَ فِي الدُّنْيَا وَالآخِرَةِ ‏"‏ ‏.‏ ثُمَّ أَتَاهُ فِي الْيَوْمِ الثَّالِثِ فَقَالَ يَا نَبِيَّ اللَّهِ أَىُّ الدُّعَاءِ أَفْضَلُ قَالَ ‏"‏ سَلْ رَبَّكَ الْعَفْوَ وَالَعَافِيَةَ فِي الدُّنْيَا وَالآخِرَةِ فَإِذَا أُعْطِيتَ الْعَفْوَ وَالْعَافِيَةَ فِي الدُّنْيَا وَالآخِرَةِ فَقَدْ أَفْلَحْتَ ‏"‏ ‏.‏