淨名經集解關中疏 2.372

2.372

曰。此飯勢力至于七日然後乃消　此四正益有三。此初七日消治四大病也。故律中有七日藥。以藥勢相接七日可知。

He said: "The potency of this rice lasts up to seven days, and only then is it digested." / This fourth [point], the actual benefits, has three. This first is digesting in seven days to cure the illnesses of the four great elements. Therefore, in the Vinaya there is seven-day medicine; that medicine's potency continues for seven days can be known.