ひゃくにちのせっぽうへひとつ

百日の説法屁一つ

表記・読み：ひゃくにちのせっぽうへひとつ

1. 1

   single mistake which ruins all one's hard work; one blunder rendering a long period of effort useless; one fart in a hundred days of sermons

   expressions (phrases, clauses, etc.)idiomatic expressionproverb