10 When Saul and his party got to Gibeah, there were the prophets, right in front of them! Before he knew it, the Spirit of God came on Saul and he was prophesying right along with them. 11 When those who had previously known Saul saw him prophesying with the prophets, they were totally surprised. "What's going on here? What's come over the son of Kish? How on earth did Saul get to be a prophet?" 12 One man spoke up and said, "Who started this? Where did these people ever come from?" That's how the saying got started, "Saul among the prophets! Who would have guessed?!"
Matthew Henry's Commentary on 1 Samuel 10:10-12
Commentary on 1 Samuel 10:9-16
(Read 1 Samuel 10:9-16)
The signs Samuel had given Saul, came to pass punctually; he found that God had given him another heart, another disposition of mind. Yet let not an outward show of devotion, and a sudden change for the present, be too much relied on; Saul among the prophets was Saul still. His being anointed was kept private. He leaves it to God to carry on his own work by Samuel, and sits still, to see how the matter will fall.