Albert Barnes Commentary 2 Samuel 2:4

"And the men of Judah came, and there they anointed David king over the house of Judah. And they told David, saying, The men of Jabesh-gilead were they that buried Saul." — 2 Samuel 2:4 (ASV)

David had already been anointed by Samuel (1 Samuel 16:13). His first anointing indicated God’s secret purpose; his second, the accomplishment of that purpose. (Compare the case of Saul, 1 Samuel 10:1; 1 Samuel 11:14.) David was anointed again king over Israel (2 Samuel 5:3). The interval between the anointing of the Lord Jesus as the Christ of God and His taking to Himself His kingdom and glory seems to be typified in this way.