1 Samuel 16:11-14

Then he asked Jesse, “Are these all the sons you have?” Jesse answered, “I still have the youngest son. He is out taking care of the sheep.” Samuel said, “Send for him. We will not sit down to eat until he arrives.” So Jesse sent and had his youngest son brought in. He was a fine boy, tanned, and handsome. The LORD said to Samuel, “Go, appoint him, because he is the one.” So Samuel took the container of olive oil and poured it on Jesse’s youngest son to appoint him in front of his brothers. From that day on, the LORD’s Spirit worked in David. Samuel then went back to Ramah. But the LORD’s Spirit had left Saul, and an evil spirit from the LORD troubled him.