Albert Barnes on Acts 9:4

And he fell to the earth. He was astonished and overcome by the sudden flash of light. There is a remarkable similarity between what occurred here, and what is recorded of Daniel in regard to the visions which he saw, Dan 8:17. Also Dan 10:8, "Therefore I was left alone, and saw this great vision; and there remained no strength in me, for my comeliness (vigour) was turned into corruption, and I retained no strength." The effect was such as to overpower the body.

And heard a voice. The whole company heard a voice, Acts 9:7, but did not distinguish it as addressed particularly to Saul. He heard it speaking to himself.

Saying unto him, etc. This shows that it was not thunder, as many have supposed. It was a distinct articulation or utterance, addressing him by name.

Saul, Saul. A mode of address that is emphatic. The repetition of the name would fix his attention. Thus Jesus addresses Martha, Lk 10:41 and Simon, Lk 22:31; and Jerusalem, Mt 23:37.

Why. For what reason, Jesus had done him no injury; had given him no provocation. All the opposition of sinners to the Lord Jesus, and his church, is without cause. Jn 15:25, "They hated me without a cause."

Persecutest. Mt 5:11.

Thou me? Christ and his people are one, Jn 15:1-6. To persecute them, therefore, was to persecute him, Mt 25:40,45.

(b) "to kick" Acts 5:39 (*) "pricks" "goads"