首楞嚴義疏注經 5.281

5.281

迦葉兄弟即三迦葉也。宣說因緣即三諦法。因說生解，悟真空理得初果證，即慧眼也。餘處即說遇馬勝者，或同時所遇，非獨一人，經互舉耳。既聞因緣，因緣即空，即獲慧眼，見真諦理。

The Kāśyapa brothers are the three Kāśyapas. Expounding causes and conditions refers to the teaching of the three truths. Generating understanding due to their exposition, he awakened to the principle of true emptiness and attained the realization of the first fruit; this is the wisdom-eye. Other places speak of encountering Assaji (Aśvajit); perhaps he met them at the same time, not just one person, and the sūtras mention them interchangeably. Having heard of causes and conditions, and causes and conditions being empty, he then attained the wisdom-eye and saw the principle of the truth of reality.