1 Samuel 7:3-6, 10

And Samuel said to all the house of Israel, “If you are returning to the LORD with all your heart, then put away the foreign gods and the Ashtaroth from among you and direct your heart to the LORD and serve him only, and he will deliver you out of the hand of the Philistines.” So the people of Israel put away the Baals and the Ashtaroth, and they served the LORD only. Then Samuel said, “Gather all Israel at Mizpah, and I will pray to the LORD for you.” So they gathered at Mizpah and drew water and poured it out before the LORD and fasted on that day and said there, “We have sinned against the LORD.” And Samuel judged the people of Israel at Mizpah.

As Samuel was offering up the burnt offering, the Philistines drew near to attack Israel. But the LORD thundered with a mighty sound that day against the Philistines and threw them into confusion, and they were defeated before Israel.