10 And when they came to Gibeah, a band of prophets came face to face with him; and the spirit of God came on him with power and he took his place among them as a prophet. 11 Now when Saul's old friends saw him among the band of prophets, the people said to one another, What has come to Saul, the son of Kish? Is even Saul among the prophets? 12 And one of the people of that place said in answer, And who is their father? So it became a common saying, Is even Saul 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.