What does 1 Samuel 7:9 mean?

The Philistines heard that all of Israel had gathered at Mizpah. In their minds, the only explanation for this congregation was preparing for battle. Rather than being caught off guard, the five lords of the Philistines assembled their armies and marched toward Mizpah to defeat the Israelites before they could launch their rebellion (1 Samuel 7:7).

However, the people of Israel were not planning an attack. Instead, they gathered to repent from their sin. They met to ask God to deliver them from the Philistines (1 Samuel 7:3–6). Now, though, the Philistines were approaching fast.

In response to the urging of the people (1 Samuel 7:8), Samuel offers an un-weaned—"nursing," or "suckling"—lamb as a whole burnt offering before the Lord. Animals could be sacrificed to the Lord once they were eight days old (Leviticus 22:27). The purpose of using the whole animal as a burnt offering was usually for atonement (Leviticus 1:4).

In addition to the offering, Samuel verbally calls out to God on behalf of His people Israel. The Lord hears and answers Samuel. The answer is apparently given in the form of what the Lord does next to spare His people from the Philistines.