Fasting in Ramadhaan is a pillar from the five pillars of Islaam, so it is one of the five great pillars. As such the one who neglects this pillar or falls short in its performance is worthy of a painful punishment in the hereafter in addition to the punishment that he should receive in this life from the punishments imposed by the Khilafah state. Here is a collection of ahaadeeth and reports (aathaar) that warn against breaking fast in Ramadhaan:
1) Abi Umaamah (ra) said: I heard the Messenger of Allah (saw) saying:
“Whilst I was asleep two men came with me and took me by my arm... He said: Then we saw a people hanging by their tendons, the corners of their mouths were cracked and blooded was flowing from them. I asked: Who are these people? They said: Those are the people who broke their fasts before its time...”
An-Nisaa’i (3273) in his As-Sunan Al-Kubraa. Ibn Hibbaan, Ibn Khuzaimah, Al-Bayhaqi, Al-Haakim and At-Tabaraani in his Al-Mu’jam Al-Kabeer also narrated it. It has been verified as being saheeh by Al-Haakim, Adh-Dhahabi and Al-Haithami.
2) Ibn Mas’ood (ra) said:
“Whoever breaks a day of fasting in Ramadhaan without a rukhsah (sharee’ah permission) he will meet Allah with it and even if he fasts the entire time after that, if Allah wills he will be forgiven and if he wills he will be punished”.
At-Tabaraani in al-Mu’jam al-Kabeer (9575/9). Al-Haithami said that its people (narrators) are trust worthy. Ibn Hazm also narrated it with different wording and it was narrated by At-Tirmidhi (719), Abu Daawud, Ibn Maajah, Ahmad, Ad-Daaraqutni, Al-Bayhaqi and Ad-Daarami from Abu Hurairah (ra).
3) Abu Hurairah (ra):
“A man broke his fast in the day of Ramadhaan so Abu Hurairah said: The fast of a year will not be accepted from him”.
Ibn Hazm (184/6) in Al-Muhalla. In another narration also from Ibn Hazm (184/6):
“Whoever (unlawfully) breaks a fast of Ramadhaan then no day from the days of the dunya can make up for it”.
Ibn Abi Shaibah (516/2) narrated that Ali (ra) said:
“Whoever misses or breaks his fast intentionally then the entirety of time will never make up for that”.
4) On the authority of Abi Marwan:
“Ali ibn Abi Taalib (ra) came upon An-Najaashi who had drunk alcohol in Ramadhaan so he lashed him eighty times. He then lashed him twenty times the following day saying: We lashed you twenty for your going against Allah and your breaking of fast in Ramadhaan”.
Ibn Hazm in his Al-Muhalla (184/6) and At-Tahaawi and its sanad (chain) is Saheeh. An-Najaashi in this hadeeth refers to a poet called Qays ibn Al-Haarithi. ‘Ali (ra) ordered his whipping so he fled to Mu’aawiyah.
Therefore the hadeeth and the three (or five) Aathaar (reports not from the Prophet (saw)) provide a clear indication and meaning of the great sin attributed to the one who breaks just one fast in the month of Ramadhaan. So what about the one who does not fast a whole month or many months??
The one who studies these ‘Aathaar with precision will find from the wording used in them that they are unlikely to represent the understandings of the Sahaabah or their Ijtihaadaat. Statements like this are very far away from the likelihood of originally being from them. With that said I do not regard them as evidences, but rather they are signs (indications) and Sharee’ah rules which are valid to be accepted and it is allowed to make taqleed (imitation and following) for the one who made the statement.