Albert Barnes Commentary 1 Samuel 16:2

"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." — 1 Samuel 16:2 (ASV)

It was the purpose of God that David should be anointed at this time as Saul’s successor, and as the ancestor and the type of His Christ. It was not God’s purpose, however, for Samuel to stir up a civil war by setting up David as Saul’s rival.

Secrecy, therefore, was a necessary part of the transaction. But secrecy and concealment are not the same as duplicity and falsehood. The concealment of a good purpose, for a good end, is clearly justifiable. Therefore, there is nothing at all inconsistent with the truth in the events related here. Compare Exodus 7:16, Exodus 8:1, and Exodus 9:13.