1 Samuel 16:1-2, 6-7

And Jehovah said unto Samuel, How long wilt thou mourn for Saul, seeing I have rejected him from being king over Israel? fill thy horn with oil, and go: I will send thee to Jesse the Beth-lehemite; for I have provided me a king among his sons. And Samuel said, How can I go? if Saul hear it, he will kill me. And Jehovah said, Take a heifer with thee, and say, I am come to sacrifice to Jehovah.

And it came to pass, when they were come, that he looked on Eliab, and said, Surely Jehovah’s anointed is before him. But Jehovah said unto Samuel, Look not on his countenance, or on the height of his stature; because I have rejected him: for Jehovah seeth not as man seeth; for man looketh on the outward appearance, but Jehovah looketh on the heart.