약속이었다

In a sentence

• 그 일은 우리가 마치기로 한 약속이었다.

  That task was a promise we had agreed to complete.

  In this sentence, '약속이었다' refers to a mutual commitment made for completing the task.

• 그가 내게 준 선물은 그의 사랑의 약속이었다.

  The gift he gave me was a promise of his love.

  Here, '약속이었다' signifies the symbolic representation of his love through the gift.

• 그건 인간으로서 지켜야 할 도덕적 약속이었다.

  That was a moral promise that one should uphold as a human.

  In this case, '약속이었다' denotes an ethical commitment inherent to human responsibility.