God makes a covenant with David.  Consider:

• God Is Great – David acknowledges the greatness of God. There are none like God; indeed he is the only God.  According to his greatness, God has made promises to David, and called Israel to be his people.  Ponder God’s greatness, and his greatness to you!
• God’s Promises – In 17:9-10, God promises to subdue their enemies that Israel might dwell in peace. In chapter 18, God fulfills his promise, giving David victory over his enemies (v6, 13).  We can trust his promises; he will not fail.  What promises of God do you need to cling to today?