Does sexual intercourse in the anus (dubar) invalidate Hajj?
Chapter on What the Muhrim Must Avoid and What is Permissible for Him
Al-Mughni
Book of Hajj
Primary text
Sexual intercourse, whether with a human or an animal, and whether in the vagina (qabl) or the anus (dubar), is considered the same regarding legal rulings unless otherwise specified. The dominant view holds that intercourse in the anus invalidates Hajj. This is because sexual intercourse that necessitates ritual purification (ghusl) invalidates Hajj, analogous to intercourse in the vagina with a human being. Intercourse without ejaculation is distinguished from intercourse that necessitates major consequences like the fixed punishment (hadd) or dowry.
Supporting text
Abu Thawr related from Abu Hanifa that sodomy and intercourse in the anus do not invalidate Hajj because they do not establish the ruling of being 'muhsan' (married/chaste status for penal purposes), resembling intercourse that does not involve the vagina.