人の噂も七十五日 (ひとのうわさもしちじゅうごにち): a wonder lasts but nine days; gossip lasts just 75 days

a wonder lasts but nine days; gossip lasts just 75 days

Gossip about a person lasts seventy five days. Comfort for someone mortified by something everyone will have forgotten by the season after next.

A Japanese proverb (ことわざ)