四部律并論要用抄 2.44

2.44

過畜七日藥戒　何故制限七日者。藥勢相接七日可知故也　僧祇云。若食上多有藥食不盡得。以苲作漿作非時受。若有餘緣不得苲。即應作是言。此中淨物生我當受。蘇蜜亦如是。得作七日服。凡服藥先漱口洗手。然後服之。四藥不足如酪。是時藥作蘇即為七日藥。燒作灰即作為盡形藥。文煩不廣釋也。

The precept on keeping seven-day medicines beyond the limit.
Why is the limit set at seven days? Because the potency of the medicine lasts for seven days, as can be known. The Mahāsāṃghika-vinaya states: If upon food there is much medicine and the food cannot be finished, one may press it to make a syrup and receive it as an out-of-season [medicine]. If due to other circumstances one cannot press it, one should say, “When pure matter arises from this, I shall receive it.” Ghee and honey are also like this; they may be taken as seven-day medicine. Whenever taking medicine, first rinse the mouth and wash the hands, and only then consume it. If the four medicines are deficient, like curd, this is a seasonal medicine; when made into ghee, it becomes a seven-day medicine; when burned to ash, it becomes a lifetime medicine. The text is elaborate, so it is not explained in full.