The fast is invalidated by intentionally engaging in any ma‘ṣiyah [act of disobedience] – whichever ma‘ṣiyah it may be, without exception – if it was done intentionally while aware of one’s fast; like being intimate with someone not permitted to him, of women or men; or kissing other than one’s wife or slave girls, of women or men; or entering the rectum of his wife or slavegirl or otherwise; or lying; or backbiting; or gossiping; or intentionally leaving off the ṣalāh [prayer]; or tyranny; or doing other things that are forbidden for a person to do.

The burhān [proof] of that is what ‘Abd Allāh Ibn Yūsuf told us: Aḥmad Ibn Fatḥ told us: ‘Abd Al-Wahhāb Ibn ‘Īsā told us: Aḥmad Ibn Muḥammad told us: Aḥmad Ibn ‘Alī told us: Muslim Ibn Al-Ḥajjāj told us: Muḥammad Ibn Rāfi‘ told me: ‘Abd Ar-Razzāq told us: Ibn Jurayj told us: ‘Aṭā‛ informed me: from Abū Ṣāliḥ Az-Zayyāt – he is As-Sammān – that he heard Abū Hurayrah saying: Allāh’s Messenger (ṣallallāhu ‘alay-hi wa-sallama) said: «والصيام جنة فإذا كان يوم صوم أحدكم فلا يرفث يومئذ ولا يسخب فإن سابّه أحد أو قاتله فليقل إني صائم»: “Fasting is a shield; so if it is the day of the fast of any of you, then he must not yarfath [be obscene] on that day and must not yaskhab [be loud, i.e. in argumentation]; so if someone insults him or fights him, then he must say: I am fasting.”

[Abū Ḥ***ān: ‘Abd Ar-Razzāq is famous and accepted by many, but some doubt surrounds him due to statements against him by those who met him; however, this narration is authentically reported by Abū ‘Awānah: from Ad-Daqqāq: from Rawḥ: from Ibn Jurayj: do.]

It was related to us via Mālik: from Abu’z-Zinād: from Al-A‘raj: from Abū Hurayrah: that Allāh’s Messenger (ṣallallāhu ‘alay-hi wa-sallama) said: «الصيام جنة فإذا كان أحدكم صائما فلا يرفث ولا يجهل فإن امرؤ قاتله أو شاتمه فليقل إني صائم»: “Fasting is a shield; so if one of you are fasting, then he must not yarfath [be obscene] and must not yajhal [be ignorant]; so if a person fights him or insults him, then he must say: I am fasting.”

‘Abd Ar-Raḥmān Ibn ‘Abd Allāh Ibn Khālid told us: Ibrāhīm Ibn Aḥmad told us: Al-Farbarī told us: Al-Bukhārī told us: Ādam Ibn Abī Iyās told us: Ibn Abī Dhi‛b told us: Sa‘īd Ibn Abī Sa‘īd Al-Maqburī told us: from his father: from Abū Hurayrah: that the Prophet (ṣallallāhu ‘alay-hi wa-sallama) said: «من لم يدع قول الزور والعمل به فليس لله حاجة في أن يدع طعامه وشرابه»: “Whoever does not leave saying zūr [falsehood] and acting by it, then Allāh has no ḥājah [need] for him to leave his food and his drink.”

‘Abd Allāh Ibn Rabī‘ told us: ‘Abd Allāh Ibn Muḥammad Ibn ‘Uthmān told us: Aḥmad Ibn Khālid told us: ‘Alī Ibn ‘Abd Al-‘Azīz told us: Al-Ḥajjāj Ibn Al-Minhāl told us: Ḥammād Ibn Salamah told us: from Sulaymān At-Taymī: from ‘Ubayd, the mawlā of Allāh’s Messenger (ṣallallāhu ‘alay-hi wa-sallama): that Allāh’s Messenger (ṣallallāhu ‘alay-hi wa-sallama) came across two fasting women who were backbiting the people, so he said to them: «قيئا»: “Vomit!” So they vomited pus, blood, and fresh meat. He then said: «ها إن هاتين صامتا عن الحلال وأفطرتا على الحرام»: “O! These two fasted from the ḥalāl and broke fast on the ḥarām.”

Abū Muḥammad [Ibn Ḥazm] said: He (‘alay-hi’s-salāmu) thus forbade rafath [obscenity] and jahl [ignorance] during the fast; so whoever did anything of that – intentionally while aware of his fast – did not fast as he was commanded; and the one who did not fast as he was commanded did not fast; this is because he did not implement the fasting with which Allāh (ta‘ālā) commanded him, i.e. (the fasting) which is free of rafath and jahl, and these are two names that encompass every ma‘ṣiyah [act of disobedience].

He (‘alay-hi’s-salāmu) informed us that whoever does not leave speaking bāṭil [something invalid] – and that is zūr [falsehood] – and does not leave acting by it, then Allāh (ta‘ālā) has no ḥājah [need] for abandoning one’s food and drink. It is thus verified that Allāh (ta‘ālā) is not pleased with that fast and He does not accept it; and if He is not pleased with it and He does not accept it, then it is bāṭil and sāqiṭ [a failure]; and he (‘alay-hi’s-salāmu) informed that the backbiting woman broke her fast, and no one is capable of opposing this.

[Abū Ḥ***ān: Ibn Ḥazm then refutes those who claim that only the reward is invalidated, not the act; then he shows his opinion is shared by many of the Salaf from the Ṣaḥābah, including: ‘Umar, ‘Alī, Abū Hurayrah, Abū Dharr, Anas Ibn Mālik, and Jābir Ibn ‘Abd Allāh; and from the Tābi‘īn, including: Mujāhid, Ḥafṣah Bint Sīrīn, Maymūn Ibn Mihrān, and Ibrāhīm An-Nakha‘ī. He then continued to refute his opponents by showing the contradictions between those who reject this but accept that other things – aside from food, drink and sex – break the fast.]

Source: Al-Muhalla, Ibn Hazm, Issue 734.