瑜伽師地論略纂 11.97

11.97

論解菩薩不應於菩薩藏未精研究，於菩薩藏一切棄捨，於聲聞藏一向修學，是犯，何故不云若於菩薩藏已精研究，方學聲聞藏，非是違犯也？答曰：以菩薩但有日分三時學，未有於菩薩藏已精研究，捨大學小乘，故於次下戒一時總開無犯。日分三時：二分修佛語，一分學外論，則小乘與外論，下開中義等也。

The Treatise explains that a bodhisattva should not fail to investigate the Bodhisattva-piṭaka thoroughly, completely abandon the Bodhisattva-piṭaka, and exclusively cultivate and study the Śrāvaka-piṭaka, which is an offense. Why does it not say that if one has already thoroughly investigated the Bodhisattva-piṭaka and only then studies the Śrāvaka-piṭaka, it is not a transgression? The answer: Because a bodhisattva only has the three periods of the daytime for study; there is no case where one has already thoroughly investigated the Bodhisattva-piṭaka and abandons the Great Vehicle to learn the Small Vehicle; therefore, in the subsequent precept, it is generally permitted at one time without offense. The daytime is divided into three periods: two parts cultivate the Buddha's words, and one part studies non-Buddhist treatises; thus the Small Vehicle and non-Buddhist treatises have an equivalent meaning under the exception below.