An oral message passed through someone (a communication by word of mouth); also used for hearsay or rumor. Slightly old-fashioned or literary.
親友からの言伝で、彼が結婚したと聞いた。
I heard from a friend (by word of mouth) that he got married.
部長の言伝を受けて、会議の資料を準備した。
I received a message from the manager and prepared the meeting materials.
それはただの言伝だと伝えておいた方がいい。
You should let them know that's only a rumor/hearsay.