Intercourse in the back passage is a major sin which is emphatically forbidden in sharee’ah.
This has been explained in the answer to question no. 1103.
The intercourse that is forbidden is when the head of the penis disappears into the back passage, with or without a barrier, and even if one does not ejaculate. The ruling has to do with penetration, not with ejaculation or touching.
Al-Suyooti (may Allaah have mercy on him) said in al-Ashbaah wa’l-Nazaa’ir (458):
There is no difference whether penetration is with a cloth or not. End quote.
The fuqaha’ (may Allaah have mercy on them) have stated that it is haraam to have intercourse with a menstruating woman even if that is with a barrier.
It says in Asna al-Mataalib (1/100), and there is something similar in Tuhfat al-Muhtaaj (1/390), which are both Shaafa’i books:
Similarly it is haraam to have intercourse with her (i.e., the menstruating woman) in her vagina, even with a barrier. End quote.
After researching the matter, we could not find any difference of opinion among the scholars on this ruling. Their texts which speak of the prohibition on anal intercourse are general in meaning and include all cases, whether there is a barrier or not.
So it is not permissible to have intercourse in the back passage at all, whether it is with or without a barrier. The one who does that has to repent and seek forgiveness, and resolve not to do such a thing again. It is not permissible for the wife to respond to her husband’s request if he asks her for that. If he insists on it then she has the right to ask the qaadi for a divorce. There is no obedience to any created being if it involves disobedience towards the Creator.
Shaykh al-Islam said: If he has intercourse with her in her back passage and she did that willingly, they should both be given a disciplinary punishment (ta’zeer). If they do not stop they should be separated, as the immoral man and the one with whom he committed immoral acts should be separated. End quote.
Majmoo’ Fataawa Ibn Taymiyah (32/267).