四分律行事鈔資持記 1.455

1.455

正釋中。所以唯約受說者。由此二法，世中數用故。又人常誦，亦易解故。

In the direct explanation: the reason why it treats only the reception [of ordination] and the recitation [of the prātimokṣa] is because these two rites are frequently used in the world. Moreover, people constantly recite them, so they are also easy to understand.