Through his Spirit, the Lord equipped David in a special way for his work as king.1 With the Spirit coming upon David, at the same time he departed from Saul (1 Samuel 16:14)2 and thus confirmed that David had replaced Saul as king.3 Jesus Christ was similarly equipped and led by the Spirit after his anointing/baptism (see Matthew 3:13 – 4:11).4
Reflecting on the coming of the Spirit, it is important to realise that this was not the Spirit working to create a true faith in David’s heart. Already we’ve seen evidence that such a faith existed. David’s godly character and his humility didn't come from any good that lay within him, it was the fruit of the Spirit. In the days of the old covenant as with the new, the Spirit was working amongst God’s people. He wasn’t absent from Israel and there can be no faith apart from him. It is thus not regeneration that is in view here, but empowerment (cf. Acts 1:8) and equipping for service. Empowerment and equipping for service, specifically service as the anointed one. Service as God’s king. Service as the one who must make important decisions and lead the people into battle.
13 Then Samuel took the horn of oil and anointed him in the midst of his brothers. And the Spirit of the LORD rushed upon David from that day forward. And Samuel rose up and went to Ramah.