大毘盧遮那成佛經疏 2.23

2.23

經云「復以此施授與非親識者，是第三疱種」，謂欲成此守齋善法，修習無貪慧捨之心。由數習故善心漸增長，復能施與非親識人，見此平等施心功德利益故。爾時善萌倍復增廣，猶如牙莖滋盛未生業時，故名疱種也。

The sūtra says: "Further presenting this gift to those who are not relatives or acquaintances is the third: the bud seed." This means that wishing to accomplish this wholesome practice of observing the fast, one cultivates a mind of non-greed and wise giving. Through repeated practice, the wholesome mind gradually grows, and one is further able to give to people who are not relatives or acquaintances, seeing the merit and benefit of this mind of impartial giving. At that time, the sprout of goodness doubles in growth and expansion, just as the sprout and stem flourish before leaves are produced; therefore, it is called the "bud seed."