Where are these foreigners from anyway? I've never heard of a tradition to sacrifice sheep
It's a fairly common practice amongst Muslims - called "
dhabihah" - my dad spent a lot of time in Saudi Arabia working on oil refineries, and apparently sheep sacrifice was pretty common.
EDIT: I should note that it isn't unique to Islam - it's found in religions and cultures all over the world, including Judaism, certain sects of Hinduism, and even some instances in the New Testament.