四分律行事鈔資持記 3.455

3.455

四中，初引制法。一日即第八日。謂下，顯意。上句示間日，下句明非犯。據本不服，理應成受；制須間日，為抑貪情。又心曾服食，八日成犯，後受相染；今由不服，故得間受。立法有以，故令準用。

In the fourth, first the established rule is cited: one day means the eighth day. From "Meaning..." downward, it reveals the intent. The upper clause indicates alternating days, and the lower clause clarifies that there is no violation. If based on fundamentally not having consumed it, in principle the reception should be valid; the rule requiring an alternating day is to suppress greedy sentiments. Furthermore, if one previously intended to consume it, on the eighth day an offense is formed, and subsequent receptions are tainted; now, because it was not consumed, an alternating reception is permitted. The enactment of the rule has its reason, hence it is to be applied accordingly.