(2) Umat Islam telah sepakat bahawa berpuasa pada bulan Ramadan adalah wajib, dan dalilnya terdapat dalam Al-Qur'an dan Sunnah. Allah berfirman (terjemahan maksudnya):

(2) The ummah is agreed that fasting the month of Ramadaan is obligatory, the evidence for which is in the Qur’aan and Sunnah. Allaah says (interpretation of the meaning):

"Wahai orang-orang yang beriman! Diwajibkan atas kamu berpuasa sebagaimana diwajibkan atas orang-orang sebelum kamu, agar kamu menjadi orang-orang yang bertakwa." [al-Baqarah 2:183] Nabi ﷺ bersabda: "Islam dibina atas lima [perkara]…" antaranya baginda menyebut puasa di bulan Ramadan. (Diriwayatkan oleh al-Bukhari, al-Fath, 1/49). Sesiapa yang berbuka puasa pada bulan Ramadan tanpa uzur yang sah, maka dia telah melakukan dosa besar yang serius. Nabi ﷺ bersabda, sambil menceritakan mimpi yang baginda lihat: "… sehingga aku sampai ke gunung, di sana aku mendengar suara-suara yang kuat. Aku bertanya, 'Apakah suara-suara ini?' Mereka menjawab, 'Ini adalah raungan penghuni Neraka.' Kemudian aku dibawa [ke tempat lain], dan aku melihat orang-orang digantung pada tendon lutut mereka, dengan sudut mulut mereka koyak dan menitiskan darah. Aku bertanya, 'Siapakah mereka ini?' Mereka menjawab, 'Mereka yang berbuka puasa sebelum tiba waktunya yang sebenar,' iaitu sebelum waktu iftar." (Saheeh al-Targheeb, 1/420).

“O you who believe! Observing al-sawn (the fasting) is prescribed for you as it was prescribed for those before you, that you may become al-muttaqoon (the pious).” [al Baqarah 2:183] The Prophet (peace and blessings of Allaah be upon him) said: “Islam is built on five [pillars]…” among which he mentioned fasting in Ramadaan. (Reported by al-Bukhaari, al Fath, 1/49). Whoever breaks the fast during Ramadaan without a legitimate excuse has committed a serious major sin, The Prophet (peace and blessings of Allaah be upon him) said, describing a dream that he had seen: “… until I was at the mountain, where I heard loud voices. I asked, ‘What are these voices?’ They said, ‘This is the howling of the people of Hellfire.’ Then I was taken [to another place], and I saw people hanging from their hamstrings, with the corners of their mouths torn and dripping with blood. I said, ‘Who are these?’ They said, ‘The people who broke their fast before it was the proper time to do so,’ i.e., before the time of iftaar.” (Saheeh al-Targheeb, 1/420).

Al-Haafiz al-Dhahabi (semoga Allah merahmatinya) berkata, "Di kalangan orang-orang beriman, telah menjadi perkara yang mantap bahawa sesiapa yang tidak berpuasa di bulan Ramadan tanpa sebarang keuzuran yang sah adalah lebih buruk daripada penzina atau peminum arak; mereka meragui sama ada dia benar-benar seorang Muslim, dan mereka menganggapnya sebagai ahli bid'ah dan fasik." Shaykh al-Islam [Ibn Taymiyah] (semoga Allah merahmatinya) berkata: "Jika seseorang tidak berpuasa di bulan Ramadan sedangkan dia mengetahui bahawa perbuatan itu haram tetapi menghalalkannya bagi dirinya sendiri, maka bunuhlah dia; dan jika dia berbuat demikian kerana dia seorang yang fasik [tetapi mempercayai bahawa ia haram], maka hukumlah dia kerana tidak berpuasa." (Majmoo' al-Fataawa, 25/265).

Al-Haafiz al-Dhahabi (may Allaah have mercy on him) said, “Among the believers it is well-established that whoever does not fast in Ramadaan without a valid excuse is worse than an adulterer or drunkard; they doubt whether he is even a Muslim at all, and they regard him as a heretic and profligate.” Shaykh al-Islam [Ibn Taymiyah] (may Allaah have mercy on him) said: “If a person does not fast in Ramadaan knowing that it is haraam but making it halaal for himself to do so, kill him; and if he does it because he is immoral [but believes it is haraam], then punish him for not fasting.” (Majmoo’ al-Fataawa, 25/265).