1 Samuel 16:4

2And Samuel said, How can I go? if Saul hear it, he will kill me. And the LORD said, Take an heifer with thee, and say, I am come to sacrifice to the LORD.

3And call Jesse to the sacrifice, and I will shew thee what thou shalt do: and thou shalt anoint unto me him whom I name unto thee.

4And Samuel did that which the LORD spake, and came to Bethlehem. And the elders of the town trembled at his coming, and said, Comest thou peaceably?

5And he said, Peaceably: I am come to sacrifice unto the LORD: sanctify yourselves, and come with me to the sacrifice. And he sanctified Jesse and his sons, and called them to the sacrifice.

6And it came to pass, when they were come, that he looked on Eliab, and said, Surely the LORD’s anointed is before him.