말했다는

In a sentence

• 그가 왜 그렇게 말했다는 것을 이해할 수 있다.

  I can understand why he said that.

  Here, '말했다는' is used to introduce the reported speech or claim being understood.

• 친구가 나에게 그곳에 가지 말라고 말했다는 이야기를 들었다.

  I heard the story that my friend told me not to go there.

  In this sentence, '말했다는' connects the verb '말하다' with the subsequent clause about a story being heard.

• 선생님이 숙제를 빨리 끝내야 한다고 말했다는 사실을 기억하세요.

  Remember the fact that the teacher said we must quickly complete the homework.

  Here, '말했다는' expresses the recalled statement made by the teacher regarding an obligation.