What is the ruling on the fast of one who had intercourse with his wife in a dream after Fajr prayer in Ramadan, and does that affect the fast?

The default rule is that whoever has intercourse with his wife during Ramadan is obligated to make up the fast and offer expiation. However, if this occurred due to being overwhelmed or forgetful, scholars have differed regarding the validity of his fast. Some hold that his fast is valid, while others deem it invalid, citing the Hadith of the Bedouin who had intercourse with his wife.

Ibn Qudamah mentioned that the apparent view of Imam Ahmad is that the forgetful person is treated the same as the intentional one regarding the obligation of making up the fast and offering expiation. Ahmad ibn al-Qasim reported from him that for any matter where the fasting person is overwhelmed, there is no make-up or anything else required, and this includes duress and forgetfulness. This is the view of Al-Hasan, Mujahid, Al-Thawri, and Al-Shafi'i, by analogy with eating forgetfully. Malik, Al-Awza'i, and Al-Layth disagreed with them, obligating make-up but not expiation.

Ibn Qudamah responded by stating that the Prophet (peace be upon him) commanded expiation for the one who had intercourse and did not inquire about intentionality. If the ruling were different, he would have inquired. Furthermore, fasting is an act of worship that prohibits intercourse, so intentional and unintentional acts are treated equally, similar to Hajj. Also, the invalidation of the fast and the obligation of expiation are two rulings related to intercourse that are not waived by doubt, so intentional and unintentional acts are equal in both.

The more cautious approach is to make up the fast if intercourse occurred under duress or forgetfulness, even though our fatwa states that it is not obligatory. And Allah Almighty knows best.