مَنْ يَشَاءُ
Whom He wills.
The condition of divine will is significant. If guidance here meant only explaining the right path, that explanation could be offered to everyone reached by the message. Yet receiving the explanation and accepting it are not the same. The question at issue is thus the realization of guidance, not merely the communication of guidance.
Two people may hear the same teaching: one considers and accepts it while the other refuses. They receive an outward indication alike, but their actual inward response differs.