四分律行事鈔資持記 3.348

3.348

更量者，日中受藥，以五更為限故。日夜各五時者，無論長短，但將一日分為五時，對夜五更。（不可定約寅卯等時；以夜五更，亦不限此時故。若準《僧祇》，晝夜三十須臾，即三須臾為一時，且據相等為言。）至二更者，謂盡一更，交至二更，受法即謝。如是輪轉者，謂第二時受，即盡二更，至三更謝等。若約《四分》，但盡非時。今須依律。此下，簡濫。漬飯漿，即今之漿水也。

Regarding 'Quantity of Watches': one formally accepts medicine at midday, taking the fifth watch as the limit. Regarding 'five periods each for day and night': regardless of whether they are long or short, one merely divides a single day into five periods, corresponding to the five watches of the night. (One cannot strictly define them by the tiger (yín) or hare (mǎo) hours, etc., because the five watches of the night are also not limited to these times. If one follows the Mahāsāṃghika-vinaya, there are thirty muhūrtas in a day and night, so three muhūrtas make one period, speaking merely on the basis of equality.) 'Reaching the second watch' means that when the first watch ends and passes into the second watch, the validity of the formal acceptance expires. 'Rotating in this manner' means that if received in the second period, it extends until the end of the second watch, expiring upon reaching the third watch, and so forth. If according to the Dharmaguptaka-vinaya, it merely lasts through the untimed [period]. Now one must rely on the Vinaya. 'This...' below eliminates confusion. 'Liquid from soaked cooked rice' is precisely the fermented congee water of today.