When is david first mentioned in you Samuel?

David is first mentioned in the book of 1 Samuel in 1 Samuel 16:1-13. In this passage, God instructs the prophet Samuel to anoint David as the future king of Israel, as Saul has been rejected due to his disobedience. Samuel goes to Bethlehem, where he finds David, the youngest son of Jesse, who is tending sheep. David is anointed in the presence of his family, marking the beginning of his rise to prominence.