Narrated Abu Huraira: The Prophet said, “Allah said: The Fast is for Me and I will give the reward for it, as he (the one who observes the fast) leaves his sexual desire, food and drink for My Sake. Fasting is a screen (from Hell) and there are two pleasures for a fasting person, one at the time of breaking his fast, and the other at the time when he will meet his Lord. And the smell of the mouth of a fasting person is better in Allah’s Sight than the smell of musk.
[Ref: Sahih Bukhari, Vol.9, Book 93, Hadith 584]

1. When should one break his fast?

Once the entire disk of the sun has disappeared, the fasting person should break his fast, and not pay any attention to the red glow that remains on the horizon, because of the evidences :
We were with the Messenger of Allah (may peace be upon him) on a journey during the month of Ramadan. When the sun had sunk he said: So and so, get down (from your ride) and prepare the meal of parched barley for us. He said: Messenger of Allah, still (there is light of) day. He (the Holy Prophet) said: Get down and prepare meal of parched barley for us. So he got down and prepared the meal of parched barley and offered him, and the apostle of Allah (may peace be upon him) drank that (liquid meal).He then told with the gesture of his hand that when the sun sank from that side and the night appeared from that side, then the observer of the fast should break it.
[Ref: Sahih Muslim English reference: Book 6, Hadith 2422]
[Ref: Reported by al-Bukhaari, al-Fath, no. 1954; the issue is also mentioned in Majmoo’ al-Fataawa, 25/216]
Allaah The Almighty Says (what means): “Then complete the fast till the night [i.e. sunset].”[Quran 2:187]
Note: A person who is unable to distinguish or recognize the sunset may rely on the Maghrib adhan to break his fast

2. Be quick in breaking the fast :

Sahl Ibn Sa’d (R) said that the Messenger (PBUH) of Allah (SWT) said: “The people will continue to be in good condition (right path) as long as they hasten to break the fast.”
[Ref: Sahih Muslim, Book 6, Hadith 2417]
[Ref: Sunan Tirmidhi, Vol 2, Book 3 Hadith 699]
[Ref: Sahih Bukhari, Vol 3, Book 31, Hadith 178]
Abu Huraira (Ra) said that the Messenger of Allah (SWT) said: “The Deen will be uppermost/manifest as long as the people hasten (quicken) to break their fast because the Jews and the Christians delay (breaking their fast).”
[Ref: Narrated by Abu Dawood Book 13, Hadith 2346 and Ibn Hibbaan]
Abu Atiyyah said: “Masruq and I entered upon Aishah and we said: ‘O Mother of the Believers! There are two men from the Companions of Muhammad, one of them hastens t break the fasts and he hastens to perform Salat. The other delays breaking the fast and he delays the Salat.’ She said: ‘Which of them hastens to break the fast and hastens to perform the Salat?’ We said that it was Abdullah bin Mas’ud. She said: ‘This is how the Messenger of Allah did it.’ And the other was Abu Musa.
[Ref: Sunan Al Tirmidhi, Vol. 2 , Book 3, Hadith 702]

Saying the Pious Predecessors:

Sa’îd b. Al-Musayyib reports from his father, “I was once sitting with ‘Umar when a group of people arrived from Al-Shâm. ‘Umar enquired about them and how they were; he asked, ‘Do the people of Al-Shâm hasten to break the fast.’ He said, ‘Yes.’ [‘Umar] said, ‘They will not cease to remain upon good as long as they do this, and do not wait for the stars [to come out] as the people of Irâq do.’”
‘Abd Al-Razzâq Al-San’ânî, Al-Musannaf 4:225.
‘Amr b. Maymûn Al-Awdî reports, “The Companions of Muhammad (sallAllaahu ‘alaihi wa sallam) used to be the quickest to break the fast and the slowest in taking the pre-dawn meal.” [Ibid. p226.]
Ibn Al-Musayyib also reports that ‘Umar wrote to the commanders of the various regions, ‘Do not be of the procrastinators when breaking the fast, and nor of those who wait for the stars before they start praying [al-maghrib].’ [Ibid. p225.]
Mûsâ b. Anas reports that Anas [ibn Mâlik] used to have his slave-girl go to the top of his house, instructing her, ‘When the horizon becomes even (evenly lit, marking sunset), tell me.’ [Ibn Abî Shaybah, Al-Musannaf 2:430.]
Abû Al-Tiyâh Al-Daba’î reports that “he used to break fast with Ibn ‘Abbâs during Ramadân. When evening approached he would send a girl from his household to the roof [to look out], and when the sun set he would make the call to prayer (adhân). He would eat with us, and when he had finished, the call for the commencement of prayer {iqâmah) would be given, and he would pray, and we would pray with him.” [Ibid. p429.]

3. Breaking the fast before the Maghrib Salaah

The Prophet (peace and blessings of Allaah be upon him) would not pray Maghrib until he had broken his fast, if only with a sip of water.
[Ref: Reported by al-Haakim, 1/432; al-Silsilat al-Saheehah, 2110]
Anas Ibn Maalik said: “The Prophet (PBUH) used to break his fast with fresh dates before he prayed (maghrib). If he did not find fresh dates then he would use dried dates. If he did not find that also he drank a few sips of water.
[Ref: Musnad Ahmad]
[Ref: Abu Dawood Book 13, Hadith 2349]

4. Break the fast with dates or water.

Narrated Salman ibn Amir: The Prophet (peace_be_upon_him) said: When one of you is fasting, he should break his fast with dates; but if he cannot get any, then (he should break his fast) with water, for water is purifying.
[Ref: Sunan Abu Dawood, Book 13, Hadith 2348]

5. Make Dua before breaking the fast as much as you can

Abu Huraira said the Messenger (PBUH) of Allah (SWT) said: “The supplications of three groups of people’s are not rejected; the du’aa (Supplication) of the fasting person when he is breaking his fast, the du’aa of the just Imam and the du’aa of the oppressed.”
[Ref: Jami` at-Tirmidhi 3598, Ibn Hibbaan 3428, Ibn Maajah , Book 7, Hadith 1824; Ahmad Shaakir in ‘Umdatal Tafseer 1/416 pointed out the rightness of this; and declared it Saheeh in Musnad Ahmad 15/189; Imam al Dhahabi supported this in his al-Madhab 3/1272 and 6/3266 via Abu Hurayra (r.a); al Mundhari in Targheeb wal Tarheeb 2/121; ]

إِنَّ لِلصَّائِمِ عِنْدَ فِطْرِهِ لَدَعْوَةً مَا تُرَدُّ

It was narrated from ‘Abdullah bin ‘Amr bin ‘As that the Messenger of Allah (sallallahu ‘alaihi wa sallam) said:
“When the fasting person breaks his fast, his supplication is not turned back.
[Ibn Maajah, English version : Vol. 1, Book 7, Hadith 1753, al Busayri has classified this as Isnaadu Saheeh in إتحاف الخيرة المهرة , 3/102, Ibn Hajar Asqalaani has classified this as Hassan in الفتوحات الربانية, 4/342 , al-Suyuti in Jaami’ as-Sagheer 2385; Ibn Mulqin in Tuhfatul Mahtaaj, 2/97; Ibn Uthaymeen has classified this as Haasan in Majmoo’ al Fataawa Ibn Uthaymeen 261/20; ]
“Du’aa’ should be made before iftaar (breaking the fast), at Maghrib, because this combines weakness and humility, and because he is still fasting. All of these are means of having one’s du’aa’ answered. After breaking the fast, one is relaxed and happy, and may become negligent. But there is a hadeeth from the Prophet (peace and blessings of Allaah be upon him) which, if it is saheeh, shows that the du’aa’ may be made after breaking the fast. It said: ‘Thirst has gone, the veins are moist, and the reward is assured, if Allaah wills.” (Narrated by Abu Dawood; classed as hasan by al-Albaani in Saheeh Sunan Abi Dawood, 2066). This can only mean after breaking the fast. Similarly it was narrated that some of the Sahaabah said: “ O Allaah, for You I have fasted and with Your provision I have broken my fast.”
So you may pray to Allaah and say whatever du’aa’ you think is suitable.
[Shaykh Muhammad ibn ‘Uthaymeen (al-Liqaa’ al-Shahri, 8)]
This is also affirmed by the scholars of Islamweb :
Some scholars have classified the above two ahadeeth as weak, , however even if we consider the general ruling that the dua’a of a fasting person is accepted throughought ramadan, [See: Imaam al-Albaanee said Saheeh Li-Ghayrihi, Saheeh at-Targheeb Wat-Tarheeb (no.1002), Kashf us-Sataar (no.962) of Imaam Bazzaar] so one can still act upon this hadeeth.

6. Dua which could be said while breaking the fast

Umar said: The Messenger of Allaah (peace and blessings of Allaah be upon him) used to say when breaking his fast: “Dhahaba al-zama’ wa abtalat al-‘urooq wa thabata al-ajr in sha Allaah (Thirst is gone, the veins are moistened and the reward is certain if Allaah wills).”
[Ref: Narrated by Abu Dawood, 2357; al-Daaraqutni, 25. Ibn Hajar said in al-Talkhees al-Habeer (2/202): al-Daaraqutni said, its isnaad is saheeh.]
Note : there is another dua’a reported in ahadeeth but it is weak. irrespective of this, a person can make any dua in any language as much as he likes.

7. Feeding a fasting person

The Prophet (PBUH) said: “Whoever gives someone something to break the fast with, he would hove The same blessings as the fasting person and this would not reduce the blessings of the fasting person in any way ”
[Ref: Ahmed 17030, Ibn e Majah 1746 & Tirmidhi Book 8, Chapter 82, Hadith 807]

8. Do not break the fast before time

The Prophet (peace and blessings of Allaah be upon him) saw some people hanging from their hamstrings with blood pouring from the corners of their mouths, and when he asked about them, he was told that they were the people who broke their fast before it was the time to do so.”
[Ref: Saheeh Ibn Khuzaymah, no. 1986, and in Saheeh al-Targheeb, 1/420]