I know it by hearsay only.

我只是听说而已。

《新英汉大辞典》

I don't pretend to be intimately acquainted with the mode of living customary in those days at Wuthering Heights: I only speak from hearsay; for I saw little.

我不能假装很熟悉那些日子里呼啸山庄中的日常生活方式：我只是听说：因为我见到的很少。

youdao

We have only hearsay for that.

我们只是听说那些。

youdao

It is only hearsay.

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