I Samuel 16:1, 6-7, 12-13

Now the LORD said to Samuel, “How long will you mourn for Saul, seeing I have rejected him from reigning over Israel? Fill your horn with oil, and go; I am sending you to Jesse the Bethlehemite. For I have provided Myself a king among his sons.”

So it was, when they came, that he looked at Eliab and said, “Surely the LORD’s anointed is before Him!” But the LORD said to Samuel, “Do not look at his appearance or at his physical stature, because I have refused him. For the LORD does not see as man sees; for man looks at the outward appearance, but the LORD looks at the heart.”

So he sent and brought him in. Now he was ruddy, with bright eyes, and good-looking. And the LORD said, “Arise, anoint him; for this is the one!” Then Samuel took the horn of oil and anointed him in the midst of his brothers; and the Spirit of the LORD came upon David from that day forward. So Samuel arose and went to Ramah.