(I Samuel 9:3 - Saul's father's donkeys were lost and so the father, Kish, sent his son Saul to go find them!)
While it made me laugh, this was not the correct answer! The correct answer was: Saul offered an unlawful sacrifice.
(I Samuel 13:8-14 describes this. Also, Leviticus 10:1-2 relates what happened to Nadab and Abihu, who offered unlawful fire before God a few hundred years earlier.)
Saul was not a Levite, so for him to sacrifice a burnt offering was not acceptable. Sounds like something Belloq would do..errr...did. Whoops!
I wonder whatever happened to Kish's donkeys...