Ancient sources - church fathers about the Unwritten traditions

Where to read about - church fathers discussing the unwritten traditions of the church before year 400 AD. I read that Epiphanius of Salamis has said something about the unwritten traditions in his book - Ancoratus I found this https://dokumen.pub/ancoratus-0813225914-9780813225913.html But I can not find something relevant in this book by searching by keywords. Do you know other church fathers discussing the unwritten traditions and the explanations about these unwritten traditions before 400 AD? Thanks in advance.