固かたい約やく束そく

expression, noun

solemn promise; firm promise

A strong, binding promise that is not easily broken; often used in serious personal or business contexts.

• 彼かれは固かたい約やく束そくを守まもって、必かならず時じ間かん通どおりに来きた。

  He kept his solemn promise and came right on time.

• 二人ふたりは結けっ婚こんの固かたい約やく束そくを交かわした。

  The two exchanged a firm promise of marriage.