Ashtangasamgraha 5.92

5.92

dhānye purāṇakumbhasthaṃ māsaṃ khādecca pūrvavat |

rasāyanaṃ vasiṣṭhoktametat pūrvaguṇādhikam |

svasthānāṃ niṣparīhāraṃ sarvartuṣu ca śasyate ||

in grain, kept in an old jar, for a month, and eat it as before. / This rasāyana, taught by Vasiṣṭha, is superior in qualities to the previous one; / for healthy people it requires no strict regimen, and is praised in all seasons.