How to phrase "You know what they say? [quote]" in Chinese?

Question

When giving some kind of saying or folklore knowledge, in English we often say e.g.:

You know what they say? Two heads are better than one.

I want to say something similar in Chinese:

You know what they say? 天不怕地不怕，就怕老外说中国话！

I find this an amusing rhyme, and it usually gets a laugh. However, I'm not sure what to preface it with. YouDao uses semi-literal translations:

你知道他们说...
_{Nǐ zhīdào tāmen shuō...}

你知道他们怎么说...
_{Nǐ zhīdào tāmen zěnme shuō...}

But I don't know if this is actually used by Chinese speakers (outside of translations from English). Perhaps it's Engnese (reverse Chinglish) to say this, and there's a more appropriate phrase in Chinese.

Question: How to phrase "You know what they say? [quote]" in Chinese?

Answer 1

你知道他们说的什么吗

你知道他们怎么说吗

are common phrases， but not for this context。

Depends on the type of the quote， you can use

俗话说/老话说/有句话叫：folk saying

古语有云 （classical saying）

X曰 （quote from ancient scholar）

XX说 （common phrase）

A: 俗话说： 三个臭皮匠， 顶一个诸葛亮（Two heads are better than one）

B：有句话叫： 人多手乱。

A：古人云：多多益善。

B：子曰：你说得不对。

A: 高尔基说： 子没说过。

Answer 2

Yeah, there's an equivalent expression:

-俗话说得好[quote]

Answer 3

Consider:

常言道

chángyándào

ABC

F.E.
as the saying goes

常言道, 熟能生巧。
Chángyándào, shúnéngshēngqiǎo.
As the saying goes, practice makes perfect.

Which could just as easily be translated as: You know what they say, practice makes perfect.

Answer 4

W can split this into several scenario.

If u want to say or quote Something: 俗話說、俗話話、古語有云。

It u want to say question your audience to understand what the third party say:

你明佢地講乜，你明白其他人說什麼