ACTS 8:26-35

34 So the eunuch answered Philip and said, “I ask you, of whom does the prophet say this, of himself, or of some other man?”
35 Then Philip opened his mouth and beginning at this Scripture, preached Jesus to him.
Question
To whom does this reading in Isaiah refer?

34 So the eunuch answered Philip and said, “I ask you, of whom does the prophet say this, of himself, or of some other man?”