I Samuel 16:1-2, 6-7

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.” And Samuel said, “How can I go? If Saul hears it, he will kill me.” But the LORD said, “Take a heifer with you, and say, ‘I have come to sacrifice to the LORD.’

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.”