What definitively establishes the obligation of ritual ablution (Ghusl) following sexual contact?
Chapter on What Necessitates Ghusl
Al-Mughni
Book of Purification
Primary text
Ritual ablution (Ghusl) is obligatory upon the completion of sexual intercourse, irrespective of whether both parties are circumcised or whether the contact involved the circumcised areas. The obligation is established when the Prophet Muhammad (peace be upon him) stated: "When he sits between her four branches (sha'ab), and the circumcision touches the circumcision, Ghusl becomes obligatory." This ruling is supported by the narration from Abu Musa al-Ash'ari via Aisha, who confirmed the Prophet's saying, and by the narration from Abu Hurayrah: "When he sits between her four branches and exerts effort, Ghusl becomes obligatory upon him." Furthermore, a narration from Umar indicated severe penalty for those who disagreed with this definitive ruling.
Supporting text
A dissenting opinion was attributed to Dawud, who stated Ghusl is not required, citing the principle 'Water from water' (Al-Maa'u min Al-Maa'). Some companions also held that Ghusl was not required if no ejaculation occurred ('If the man performed intercourse but did not ejaculate'). This earlier concession ('Rukhsah') was later abrogated by command to perform Ghusl.