A proverb meaning that pride or arrogance precedes downfall; historical reference that the proud Heike (Taira) clan did not endure long.
会社が急成長しても慢心は禁物だ。おごる平家は久しからずというだろう。
Even if a company grows rapidly, complacency is forbidden. As the proverb goes, pride goes before a fall.
彼は成功してから態度が大きくなったが、周囲は『おごる平家は久しからず』と心配している。
He became arrogant after his success, and people worry, 'pride doesn't last long.'