Reference: as-Sahwah al-Islaamiyyah – Question 5, Page 105
Question: What is the ruling regarding narrating stories I have heard, but am unaware as to their authenticity, in the path of da’wah to some people, and likewise narrating stories which I know are fabricated [lies]?
And what is the ruling regarding narrating a hadeeth whilst I do not know whether it is authentic or weak?
Response: It is not permissible for a person, a storyteller or one who gives advice, to narrate a hadeeth and attribute it to the Messenger (sal-Allaahu ‘alayhi wa sallam) whilst he does not know if it is authentic. And it is [also] not permissible for him to narrate a hadeeth whilst he knows it to be weak. However, if he narrates a weak hadeeth to reveal it’s weakness and warn the people from it, then that is obligatory.
Likewise, he should not narrate stories which he assumes are worthy [of being narrated] without checking [their authenticity], and he should not narrate stories which he knows are fabricated, because that is being dishonest and deceiving the people.