(2) Umma imekubaliana kuwa kufunga mwezi wa Ramadhani ni wajibu, na ushahidi wake upo katika Qur'an na Sunnah. Allah anasema (tafsiri ya maana):

(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):

“Ee mlioamini! Kufunga (al-sawm) kumewekwa juu yenu kama kilivyowekwa juu ya wale waliokuwa kabla yenu, ili mpate kuwa al-muttaqoon (wacha Mungu).” [al Baqarah 2:183] Mtume ﷺ alisema: “Uislamu umejengwa juu ya nguzo tano…” miongoni mwazo akataja kufunga mwezi wa Ramadhani. (Imepokewa na al-Bukhaari, al Fath, 1/49). Yeyote anayevunja funga katika mwezi wa Ramadhani bila udhuru halali amefanya dhambi kubwa sana. Mtume ﷺ alisema, akieleza ndoto aliyoiona: “… hadi nilipofika mlimani, ambapo nilisikia sauti kubwa. Nikauliza, ‘Sauti hizi ni nini?’ Wakasema, ‘Hii ni kilio cha watu wa Motoni.’ Kisha nikapelekwa [mahali pengine], nikawaona watu wakining’inizwa kwa mishipa ya nyuma ya magoti, pembe za midomo yao zimechanika na zinadondosha damu. Nikasema, ‘Hawa ni akina nani?’ Wakasema, ‘Ni watu waliovunja funga yao kabla ya wakati wake kufika,’ yaani kabla ya wakati wa iftaar.” (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 (Mwenyezi Mungu amrehemu) alisema: "Miongoni mwa Waislamu imethibiti wazi kwamba yeyote asiyefunga Ramadhani bila udhuru halali ni mbaya zaidi kuliko mzinzi au mlevi; wanatilia shaka kama yeye ni Mwislamu hata kidogo, na wanamchukulia kuwa mzushi na mpotovu." Shaykh al-Islam [Ibn Taymiyyah] (Mwenyezi Mungu amrehemu) alisema: "Ikiwa mtu hafungi Ramadhani akijua kwamba ni haramu lakini akiifanya halali kwa nafsi yake kufanya hivyo, muueni; na ikiwa anafanya hivyo kwa sababu ni mtu mwenye uasi [lakini anaamini kwamba ni haramu], basi mwadhibuni kwa kutofunga." (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).