Shaddad ibn Aws reported that the Prophet, may Allah bless him and grant him peace, said, "The best way of asking forgiveness is 'O Allah, You are my Lord. There is no god but You. You created me and I am Your slave. I follow Your covenant and promise as much as I can. I acknowledge Your blessing and I confess to my wrong actions, so forgive me. Only You can forgive wrong actions. I seek refuge with You from the evil of what I have done.' If he says it in the evening and then dies, he will enter the Garden - or he said that he will be one of the people of the Garden. If he says it in the morning and dies that day - it is the same."  

عَنِ النَّبِيِّ ﷺ قَالَ سَيِّدُ الاسْتِغْفَارِ اللَّهُمَّ أَنْتَ رَبِّي لاَ إِلَهَ إِلاَّ أَنْتَ خَلَقْتَنِي وَأَنَا عَبْدُكَ وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ أَبُوءُ لَكَ بِنِعْمَتِكَ وَأَبُوءُ لَكَ بِذَنْبِي فَاغْفِرْ لِي فَإِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ إِذَا قَالَ حِينَ يُمْسِي فَمَاتَ دَخَلَ الْجَنَّةَ أَوْ كَانَ مِنْ أَهْلِ الْجَنَّةِ وَإِذَا قَالَ حِينَ يُصْبِحُ فَمَاتَ مِنْ يَوْمِهِ مِثْلَهُ  

Ibn 'Umar said, "We used to say this a hundred times in the assembly of the Prophet, may Allah bless him and grant him peace, 'O Lord, forgive me and turn back to me (forgive me). You are the Ever-Turning back (to his slaves), the Merciful.'"  

عَنِ ابْنِ عُمَرَ قَالَ إِنْ كُنَّا لَنَعُدُّ فِي الْمَجْلِسِ لِلنَّبِيِّ ﷺ رَبِّ اغْفِرْ لِي وَتُبْ عَلَيَّ إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ مِئَةَ مَرَّةٍ  

'A'isha said, "The Messenger of Allah, may Allah bless him and grant him peace, prayed the Duha prayer and then said, 'O Lord, forgive me and turn to me. You are the Ever-Turning back (to his slaves), the Merciful' a hundred times."  

عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ صَلَّى رَسُولُ اللهِ ﷺ الضُّحَى ثُمَّ قَالَ اللَّهُمَّ اغْفِرْ لِي وَتُبْ عَلَيَّ إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ حَتَّى قَالَهَا مِئَةَ مَرَّةٍ  

Similar to hadith 617 but with a slightly different wording.  

عَنِ النَّبِيِّ ﷺ قَالَ سَيِّدُ الاسْتِغْفَارِ أَنْ يَقُولَ اللَّهُمَّ أَنْتَ رَبِّي لاَ إِلَهَ إِلاَّ أَنْتَ خَلَقْتَنِي وَأَنَا عَبْدُكَ وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ أَبُوءُ لَكَ بِنِعْمَتِكَ وَأَبُوءُ لَكَ بِذَنْبِي فَاغْفِرْ لِي فَإِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ قَالَ مَنْ قَالَهَا مِنَ النَّهَارِ مُوقِنًا بِهَا فَمَاتَ مِنْ يَوْمِهِ قَبْلَ أَنْ يُمْسِيَ فَهُوَ مِنْ أَهْلِ الْجَنَّةِ وَمَنْ قَالَهَا مِنَ اللَّيْلِ وَهُوَ مُوقِنٌ بِهَا فَمَاتَ قَبْلَ أَنْ يُصْبِحَ فَهُوَ مِنْ أَهْلِ الْجَنَّةِ  

'Abdullah ibn 'Umar said, "I heard the Prophet, may Allah bless him and grant him peace, say, 'Turn in repentance to Allah. I turn to Him a hundred times every day."  

سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ تُوبُوا إِلَى اللهِ فَإِنِّي أَتُوبُ إِلَيْهِ كُلَّ يَوْمٍ مِئَةَ مَرَّةٍ  

'Glory be to Allah'; 'Praise be to Allah'; and 'There is no god but Allah' a hundred times."  

عَنْ كَعْبِ بْنِ عُجْرَةَ قَالَ مُعَقِّبَاتٌ لاَ يَخِيبُ قَائِلُهُنَّ سُبْحَانَ اللهِ وَالْحَمْدُ لِلَّهِ وَلاَ إِلَهَ إِلاَّ اللَّهُ وَاللَّهُ أَكْبَرُ مِئَةَ مَرَّةٍ رَفَعَهُ ابْنُ أَبِي أُنَيْسَةَ وَعَمْرُو بْنُ قَيْسٍ