Ruling on Intercourse with a Woman in her rectum
Question

Please accept my apology if this questions offends, but in the pursuit of Islamic knowledge, we cannot afford to be shy for fear that if we are not well advised, we may commit a sin.
I have been advised by a friend that there is a "qawl" (opinion) among some ulamaa' (scholars) that it is permissible to conduct anal sex (anal penetration) (between man and wife only) during the time of the wife's haydh (menstruation).
Is this correct?
Please also advise the laws and penalties relevant to it.
Praise be to Allah.Your apology is accepted. Striving to understand the rulings of Sharee'ah in this and similar matters is not haram or shameful; it is necessary.
As regards your question, anal intercourse with one's wife is a major sin, whether it occurs at the time of menstruation or not. The Prophet (Peace & Blessings of Allah be upon Him) cursed the one who does this: "Cursed is the one who approaches his wife in her rectum" (Reported by Imaam Ahmad, 2/479; see also Saheeh al-Jaami', 5865).
The Prophet  (Peace & Blessings of Allah be upon Him) also said: "The one who has intercourse with a menstruating woman, or with a woman in her rectum, or who goes to a fortune-teller, has disbelieved in what was revealed to Muhammad." (Reported by al-Tirmidhi, no. 1/243; see also Saheeh al-Jaami', 5918).
In spite of the fact that many wives of sound nature refuse this, there are some husbands who threaten their wives with divorce if they do not obey them (in this matter), and some even deceive their wives, who are too shy to ask scholars about it, into thinking that it is permissible. The Prophet (Peace & Blessings of Allah be upon Him) said that a man may approach his wife in any way he likes, from the front or the back, so long as intercourse takes place in the place from through which a child is born. There is no doubt that the rectum is the place from which waste matter is expelled, not the place from which a child is born.

Another reason why some may commit this immoral act is that they enter upon what should be a clean married life with some jaahili (ignorant) traditions and odd practices, or with memories of scenes from indecent movies, for which they have not repented to Allah.
It is known that this act is forbidden even if both partners agree to it. Mutual consent to a haram deed does not make it halal.
I ask Allah to bestow upon us a proper understanding of His religion and to make us adhere to its limits, for He is the All-Hearing, the One Who answers prayers.