What is the ruling on a husband fondling his wife's anus with his penis without penetration, and is there any health harm if proper hygiene is observed?

What is forbidden is the insertion of the penis into the anus. Anything short of that is permissible, provided it does not lead to تجاوز ذلك. The Prophet, peace and blessings be upon him, forbade approaching women in their anuses and cursed those who do so. One must stay away from this act so as not to fall into what is forbidden, and be content with what Allah has made permissible in the place of cultivation (vagina). Whoever performs insertion into the anus has committed a forbidden act, and must perform ghusl (ritual purification), repent, seek forgiveness, and not return to it.