"Almighty Allah (swt) releases from Hellfire one million persons in the last hour everyday in the month of Ramadhan; therefore pray to Almighty Allah (swt) to include you with these released ones"
It is advisable to postpone breaking one's fast until the evening/night prayers have been performed (after reciting the Magrib & Isha Prayer - if offered together), unless one is too weak to keep fasting or other people are waiting for you to break the fast.(Ref No 1759)
It is advisable to begin breaking fast with dates.& It is advisable to recite Sura Qadr at the time of breaking the fast.
It is advisable to offer food to other fasting people even if with a single date and a drink of water. Allamah Hilli in al-Risalah al-Sa'diyyah has narrated that Imam Ja'far Sadiq (as) has said, "If a believer treats another believer with a single morsel of food in Ramadhan, Almighty Allah (swt) will give him the reward of freeing thirty believing slaves and his wishes will be granted."
Recite the following supplications at the time of breaking fast:
O my Allah, for Thee, I fast, and with the food Thou gives me I break the fast, and I rely on Thee.
ALLAAHUMMA LAKA S'UMTU WA A'LAA RIZQIKA AFT'ARTUWA A'LAYKA TAWAWKKALTU
It has been narrated that Imam Ali (as) used to say the following when he would break his fast:
In the name of Allah, O Allah, we fast, and with the food Thou gives us we break the fast, an obligation we fulfill, and Thou art Hearer, Knower
BISMILLAH ALAAHUMMA LAKA S'UMNAA WA A'LAA RIZQIKA AFT'ARNAA FA—TAQABBAL MINNAA INNAKA ANTAS SAMEE—U'L'A'LEEM
It is advisable to say the following at the first bite of food taken:
In the name of Allah, the Beneficient, the Merciful, O He whose indulgence is boundless, forgive me.
BISMILLAHIR RAH'MAANIR RAH'EEM YAA WAASI—A'L MAGHFIRATI IGFIR LEE
Recite the Supplication of 'Allahumma Rabba Nuril Azeem (below)reported by Sayyid ibn Tawus and al-Kaf'aimy. This supplication brings about great merit. The Holy Prophet (saws) recommended this dua to Imam Ali (as) and said that Jibreel (as) came to me and said," Whoever in the holy month of Ramadhan before iftaar recites this dua, Allah (swt) answers his prayer, accepts his prayer and fasting, grants his ten requirements, forgives his sins, removes his grief's, makes his heart at ease, grants his wishes, makes his deeds to ascend upward with the deeds of prophets and righteous saints and on the Day of Judgement brings him to HIS presence with his face illuminated like a bright moon."
Allahumma Rabba Nuril Azeem اللهم رب النور العظيم
O Lord of the magnificent light, Lord of the highest heaven, Lord of the flowing seas, Lord of the great intercessor and brilliant light, Lord ot fhe Tawrat and Injil, and the grand Furqan(criterion).
You are the only God of the heavens and the earth. There is no other god save you.
You are powerful over everything in the heavens and earth. There is no powerful save you.
You are the owner of the heavens and earth. There is no owner save you.
I beseech you through your great name, your brilliant superior being, your ever existing kingdom, O Ever living, O Self –Subsisting, O Ever living, O self Subsisting.
I beseech you in thy name that illuminates everything and by thy name that radiates in the heavens and earth, thy name which sets the people of all times on the right path from the foremost to the last.
O Ever Living who was there before anything else. O Ever Living who is ever existing when no life shall exist.
O Ever Living there is no god save You. Peace be upon Mohammed and his progeny.
Forgive me my sins, make my affairs easy, and the reappearance near and keep us firm in the religion of Mohammed and family of Mohammed, on the guidance of Mohammed and family of Mohammed, on the sunnah of Mohammed and his family, peace be upon him and his family.
Make my deeds lofty and accepted. Bestow upon me like you have granted your pious and obedient servants.
For surely I am a believer in you, trusting in you, turning repentantly to you, to you is my journeys end.
Gather for me and for my family and my parents all good and remove for me , my family and parents all evil. You are the compassionate, the supporter and the originator of the heavens and the earth.
Give me the best that you wish and protect me from your grace, o Kind and compassionate.
اللّٰهُمَّ رَبَّ النُّوْرِ الْعَظِيْمِ وَ رَبَّ الْكُرْسِيِّ الرَّفِيْعِ وَ رَبَّ الْبَحْرِ الْمَسْجُوْرِ وَ رَبَّ الشَّفْعِ الْكَبِيْرِ وَ النُّوْرِ الْعَزِيْزِ وَ رَبَّ التَّوْرَاةِ وَ الْإِنْجِيْلِ وَ الزَّبُوْرِ وَالْفُرْقَانِ الْعَظِيْمِ أَنْتَ إِلٰهُ مَنْ فِي السَّمَاوَاتِ وَ إِلٰهُ مَنْ فِي الْأَرْضِ لَا إِلٰهَ فِيْهِمَا غَيْرُكَ وَ أَنْتَ مَلِكُ مَنْ فِي السَّمَاوَاتِ وَ مَلِكُ مَنْ فِي الْأَرْضِ لَا مَلِكَ فِيْهِمَا غَيْرُكَ أَسْأَلُكَ بِاسْمِكَ الْكَبِيْرِ وَ نُوْرِ وَجْهِكَ الْمُنِيْرِ وَ بِمُلْكِكَ الْقَدِيْمِ يَا حَيُّ يَا قَيُّوْمُ يَا حَيُّ يَا قَيُّوْمُ يَا حَيُّ يَا قَيُّوْمُ أَسْأَلُكَ بِاسْمِكَ الَّذِيْ أَشْرَقَ بِهٖ كُلُّ شَيْءٍ وَ بِاسْمِكَ الَّذِيْ أَشْرَقَتْ بِهِ السَّمَاوَاتُ وَ الْأَرْضُ وَ بِاسْمِكَ الَّذِيْ صَلَحَ بِهِ الْأَوَّلُوْنَ وَ بِهٖ يَصْلُحُ الْآخِرُوْنَ يَا حَيُّ قَبْلَ كُلِّ حَيٍّ وَ يَا حَيُّ بَعْدَ كُلِّ حَيٍّ وَ يَا حَيُّ لَا إِلٰهَ إِلَّا أَنْتَ صَلِّ عَلٰى مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ اغْفِرْ لِيْ ذُنُوْبِيْ وَ اجْعَلْ لِيْ مِنْ أَمْرِي يُسْرًا وَ فَرَجًا قَرِيْبًا وَ ثَبِّتْنِيْ عَلٰى دِيْنِ مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَلٰى سُنَّةِ مُحَمَّدٍ وَ آلِ مُحَمَّدٍ عَلَيْهِ وَ عَلَيْهِمُ السَّلَامُ وَ اجْعَلْ عَمَلِيْ فِي الْمَرْفُوْعِ الْمُتَقَبَّلِ وَ هَبْ لِي كَمَا وَهَبْتَ لِأَوْلِيَائِكَ وَ أَهْلِ طَاعَتِكَ فَإِنِّيْ مُؤْمِنٌ بِكَ وَ مُتَوَكِّلٌ عَلَيْكَ مُنِيْبٌ إِلَيْكَ مَعَ مَصِيْرِيْ إِلَيْكَ وَ تَجْمَعُ لِيْ وَ لِأَهْلِيْ وَ وُلْدِيَ الْخَيْرَ كُلَّهٗ وَ تَصْرِفُ عَنِّيْ وَ عَنْ وُلْدِيْ وَ أَهْلِيَ الشَّرَّ كُلَّهٗ أَنْتَ الْحَنَّانُ الْمَنَّانُ بَدِيْعُ السَّمَاوَاتِ وَ الْأَرْضِ تُعْطِي الْخَيْرَ مَنْ تَشَاءُ وَ تَصْرِفُهٗ عَمَّنْ تَشَاءُ فَامْنُنْ عَلَيَّ بِرَحْمَتِكَ يَا أَرْحَمَ الرَّاحِمِيْنَ.
2 - عنه البحار 98 : 10 ، المستدرك 7 : 360
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Source: duas.org