'Certainly' in the Bible

Then David inquired of the Lord: “Should I go to war against the Philistines? Will you hand them over to me?”The Lord replied to David, “Go, for I will certainly hand the Philistines over to you.”

We will certainly die and be like water poured out on the ground, which can’t be recovered. But God would not take away a life; He would devise plans so that the one banished from Him does not remain banished.