What is the ruling on a man having anal sex with his wife, and what is the authenticity of the Hadith: "Whoever has intercourse with a menstruating woman, or a woman in her anus, or goes to a soothsayer and believes him, has disbelieved in what was revealed to Muhammad (peace and blessings of Allah be upon him)," and does "disbelief" here mean apostasy from Islam?

For a man to approach his wife anally is forbidden and among the major sins, the perpetrator of which the Prophet, peace and blessings be upon him, cursed, saying: "Cursed is he who approaches a woman in her anus," and "Allah will not look at a man who has intercourse with his wife in her anus." The disbelief mentioned in the hadith does not signify apostasy from the religion, but rather it is an intensification and emphasis on the gravity of this reprehensible act.