俱舍論頌疏論本 30.16

30.16

[The phrase] "He did not speak of [a soul] within the aggregates… because they lacked the power to understand true emptiness" clarifies the reason for not speaking of a nominal soul. A nominal soul is the principle of true emptiness; the questioner was foolish and was not a vessel capable of receiving the Dharma, hence the Buddha did not speak of it.