From the Quran
1. Surah Al-Baqarah verse 187
""It is made lawful for you to go in unto your wives on the night of the fast; they are a garment for you and you are a garment for them. Allah knows that you could not restrain your lusts, so He accepted your repentance and pardoned you. So now go in unto them and seek what Allah has ordained for you, and eat and drink until the white thread of dawn becomes distinct to you from the black thread. Then complete the fast until the night..." (QS. Al-Baqarah: 187)
Meaning: This verse explains that breaking the fast begins when night falls, namely after sunset.
2. Surah Al-Baqarah verse 184
"And for him who finds it difficult to do it, he must pay a fidyah, which is to feed a poor person. But whoever does good voluntarily, it is better for him, and to fast is better for you, if you only knew." (QS. Al-Baqarah: 184)
Meaning: This verse confirms that there is leniency for those who are unable to fast, including breaking the fast by paying fidyah..
Sahih Hadith about Breaking the Fast
1. The importance of breaking the fast quickly
The Messenger of Allah (ﷺ) said:
"People will always be in goodness as long as they hasten to break their fast." (Narrated by Bukhari No. 1957, Muslim No. 1098)
2. Breaking the fast with dates or water
From Anas bin Malik (may Allah be pleased with him), he said:
"The Messenger of Allah ﷺ used to break his fast with a few ruthab (wet dates) before prayer. If he did not have any, he would break his fast with tamr (dried dates). If he did not have any, he would take a few sips of water." (Narrated by Abu Dawud, No. 2356, Tirmidhi, No. 696, Hasan Sahih)
3. Prayer for breaking the fast
From Abdullah bin Umar (may Allah be pleased with him), the Messenger of Allah (peace and blessings of Allah be upon him) said:
“He who has been given a reward, and has been given a reward in the name of Allah.” (HR. Abu Dawud No. 2357, Hasan)
(Meaning: "The thirst has disappeared, the veins have become wet, and the reward has been established, God willing.")
4. Reward for those who feed those who break their fast
The Messenger of Allah (ﷺ) said:
"Whoever feeds a fasting person to break his fast, then for him is a reward like that of the fasting person without detracting from the fasting person's reward in the slightest." (Narrated by Tirmidhi No. 807, Ibn Majah No. 1746, Ahmad No. 23518, Sahih)
5. Breaking the fast before Maghrib prayer
From Anas bin Malik (may Allah be pleased with him):
"The Messenger of Allah ﷺ did not perform the Maghrib prayer until he broke his fast, even if it was just with a sip of water." (Narrated by Ibn Hibban No. 3505, Sahih)