四分律行事鈔資持記 3.316

3.316

四藥者，攝盡一切所食之物，對治新故二種之病，通名為藥。受兼手口，俱該四藥，但時藥手口互塞，餘三竝通。淨謂說淨，唯局七日；若論護淨作淨，則通四藥。受淨二字，從法為名。

As for the "four medicines," they encompass all edible items. Because they cure both new and old illnesses, they are collectively termed "medicines." Reception involves both hands and mouth, and both apply to all four medicines; however, with timely medicine the hands and mouth are mutually precluded, whereas the other three allow both. Purification refers to declaration of purification, which is restricted solely to the seven-day [medicines]; but if one discusses protective purification and making purification, it applies to all four medicines. The two characters "reception" and "purification" take their names from the Dharma procedures.