اللَّهُمَّ تَقَبَّلْ مِنَّا رَمَضَانَ وَأَعِنَّا عَلَى صِيَامِ سِتٍّ مِنْ شَوَّالٍ
Allahumma taqabbal minna Ramadan wa a'inna 'ala siyami sittin min Shawwal
O Allah, accept our Ramadan and help us fast six days of Shawwal.
The Prophet ﷺ said: "Whoever fasts Ramadan and follows it with six days of Shawwal, it is as if he fasted the entire year." The math: 30 days × 10 (each good deed multiplied) = 300 days + 6 days × 10 = 60 days = 360 days = one full year. This du'a asks for two things: acceptance of Ramadan (the hard part is over, but was it accepted?) and strength for Shawwal (the bonus round that completes the equation).
Related Du'as
اللَّهُمَّ صَلِّ عَلَى مُحَمَّدٍ وَعَلَى آلِ مُحَمَّدٍ كَمَا صَلَّيْتَ عَلَى إِبْرَاهِيمَ وَعَلَى آلِ إِبْرَاهِيمَ إِنَّكَ حَمِيدٌ مَجِيدٌ
O Allah, send blessings upon Muhammad and the family of Muhammad, as You sent blessings upon Ibrahim and the family of Ibrahim. Indeed, You are Praiseworthy and Glorious.
Sahihاللَّهُمَّ تَقَبَّلْ مِنَّا إِنَّكَ أَنْتَ السَّمِيعُ الْعَلِيمُ وَتُبْ عَلَيْنَا إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ
O Allah, accept from us, for You are the All-Hearing, the All-Knowing. And turn to us in mercy, for You are the Acceptor of repentance, the Most Merciful.
Sahihإِنِّي صَائِمٌ إِنِّي صَائِمٌ
I am fasting, I am fasting. (Say this when provoked while fasting.)
Sahihاللَّهُمَّ لَكَ صُمْتُ وَعَلَى رِزْقِكَ أَفْطَرْتُ
O Allah, for You I have fasted and with Your provision I break my fast.
Hasan