question #1 Sahih Muslim Introduction 59, Introduction, Narration 58 : What is the significance of verifying the authenticity of hadiths before narrating them?

‘I heard Jābir talking about something like 30,000 Ḥadīth [that] I did not regard as permissible to mention anything from, and that to me was like this and that [Ḥadīth].’Muslim said, I heard Abū Ghassān Muhammad bin Amr ar-Rāzī say, ‘I asked Jarīr bin Abd il-Hamīd: ‘Did you meet al-Hārith bin Hasīrah? He said: ‘Yes, [he is a] Shaykh of lengthy silence; he persisted in a grave matter.’