Charles Spurgeon Commentary Acts 9:5

"And he said, Who art thou, Lord? And he [said], I am Jesus whom thou persecutest:" — Acts 9:5 (ASV)

And he said, "Who are you, Lord?" And the Lord said, "I am Jesus whom you persecute. It is hard for you to kick against the pricks."

I do not doubt that he had already been pricked in his conscience, and he had kicked out as an ox kicks against the ox-goad when it is pricked by it to make it go forward. Saul was a man of strong will and determined purpose. He had already felt in his own heart some of the sorrows that follow from a wrong course of life, yet he resolved to persevere in it.

So the Lord said to him, "It is hard for you to kick against the pricks"; and if any of you resist the thrusts of conscience and the strivings of God's Spirit, you will be like a man with naked feet, kicking against iron spikes, and hurting himself, but not injuring that against which he kicks.