Does penetration into the anus invalidate the fast and necessitate Kaffarah?
General Chapter
Al-Mughni
Book of Fasting
Primary text
There is no distinction regarding the location of penetration; penetration of the front or rear passage (anus) invalidates the fast and necessitates Kaffarah if done deliberately, as stated by Al-Shafi'i. The reasoning is that invalidating the fast of Ramadan through sexual intercourse in the private parts mandates Kaffarah, and penetration into the anus is considered a form of intercourse.
Supporting text
According to the stronger of Abu Hanifa's two narrations, Kaffarah is not due for intercourse in the anus because it does not effect 'Ihlal' (legitimization) or 'Ihsan' (marital status for adultery punishment), thus resembling intercourse less than the private parts. However, intercourse in the anus invalidates the fast by itself, unlike lesser acts such as mere touching or foreplay below the private parts.