Is it forbidden to caress one's wife by inserting a finger into her anus to increase her arousal and prepare her for intercourse?

It is permissible for spouses to enjoy all parts of the body except for intercourse with a menstruating woman in her vagina, or anal intercourse, as there is an explicit prohibition against that. Scholars have explained the prohibition of anal intercourse by stating that it is a place of harm and impurity, and a curse has been reported against its perpetrator.

Therefore, inserting a finger into a woman's anus is forbidden, as it involves touching impurity without need, and it is a means to committing a forbidden act that may lead to anal intercourse, which is among the major sins, and may lead to sodomy. Furthermore, this act is abhorrent to sound human nature, and it imitates the West, whereas what Allah has legislated suffices without it. As for low libido, it should be treated with appropriate medication.