As the children of Israel were leaving Egypt and headed back towards the promised land, you can imagine that the site of them created quite a stir. There will at least a million of these people, many different ages, traveling across the terrain, and, as you probably can imagine, some would want to take advantage of them.
Amalek was one such nation—a band of marauders that preyed on the weak in the group, gathering what they could from the children of Israel and being a regular nuisance.
In Exodus 17:8-14, Joshua and the people fight against Amalek, but they’re unable to finish them off. God instructs Moses to write about these people, because He will finish them.
We see that this takes quite some time—since Amalek is still around in the days of King Saul. He is also commanded to utterly destroy them, and he leaves their livestock and their king. After a rebuke by Samuel, Saul finishes the work, but too late.
Why is this important? Because God always completes His promises. Sometimes they take a little longer than we’d like. Sometimes he involves people and asks them to complete the job.
What’s important in the story of Saul is that he decided that he knew better than God. He did not remember the promise, therefore he didn’t know why it was important to totally remove Amalek.
It all flows together—we need to be a people of the Word, such that we know God’s promises. We need to be people listening for God’s instruction so that we know when to move and what to do. And we need to obey completely, so that we can receive blessing instead of loss.