10 When they came there to the hill, there was a group of prophets to meet him; then the Spirit of God came upon him, and he prophesied among them. 11 And it happened, when all who knew him formerly saw that he indeed prophesied among the prophets, that the people said to one another, "What is this that has come upon the son of Kish? Is Saul also among the prophets?" 12 Then a man from there answered and said, "But who is their father?" Therefore it became a proverb: "Is Saul also among the prophets?"
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.