1 Samuel 16:2-5

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 Beth-lehem. And the elders of the city came to meet him trembling, 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.