Ah right, that Ishida's quote from Ch. 163.
Since dried persimmon is apparently good for the body, I wonder if Ishida meant it as poison against the Tokugawa, who are bad for the Toyotomi, or poison against other bad thing.
Hmm, since it's advice for Tokugawa, I kinda doubt it's meant as the former, but I don't have a clear, concrete idea on what the latter meant. Maybe something like "laughter/"weirdness" is poison against bad vibes"?