But his father and his mother knew not that it was of the LORD, that he sought an occasion against the Philistines: for at that time the Philistines had dominion over Israel.

But his parents didn't know it was God's plan. He wanted to find a reason to fight the Philistines because they ruled over Israel at that time.

King James Version

Simple English

* Work in progress - there may be occasional inaccuracies