See this passage explained in the notes on Acts 9:5, etc.
Related Commentaries of Acts 26:12
Acts 26:12-15
12 Whereupon as I went to Damascus with authority and commission from the chief priests,
13 At midday, O king, I saw in the way a light from heaven, above the brightness of the sun, shining round about me and them which journeyed with me.
14 And when we were all fallen to the earth, I heard a voice speaking unto me, and saying in the Hebrew tongue,Saul, Saul, why persecutest thou me? it is hard for thee to kick against the pricks.
15 And I said, Who art thou, Lord? And he said,I am Jesus whom thou persecutest.