The penalty for departing Arafah before sunset.
Chapter on the Description of Hajj
Al-Mughni
Book of Hajj
Primary text
A blood sacrifice (Dam) is incumbent upon one who departs before sunset, according to the majority of scholars, including Ata, Al-Thawri, Al-Shafi'i, Abu Thawr, and the companions of 'Ra'y'. This is because the departure before sunset is a breach of an obligation that does not invalidate the Hajj, similar to departing the designated boundary of Ihram from the Miqat without having entered Ihram, which necessitates a sacrifice, not invalidation.
Supporting text
Ibn Jurayh states a camel (Badanah) is due, and Al-Hasan Al-Basri states a sacrificial animal from the camels is due.