釋氏要覽 3.277

3.277

善見律云。佛使一比丘食時守寺（即今二寺有直月看堂者是）。

The Samantapāsādikā states: "The Buddha sent a bhikṣu to guard the monastery during mealtime." (This corresponds to the monthly duty monks watching over the hall in the two kinds of monasteries today.)