What did the Prophet Muhammad (saw) forbid on the Day of the battle of Khaibar?
 Narrated Muhammad bin `Ali:                     `Ali was told that Ibn `Abbas did not see any harm in the Mut'a marriage. `Ali said, "Allah's Apostle forbade the Mut'a marriage on the Day of the battle of Khaibar and he forbade the eating of donkey's meat." Some people said, "If one, by a tricky way, marries temporarily, his marriage is illegal." Others said, "The marriage is valid but its condition is illegal."