如何使用 as an old saying goes

客人:
Good morning. My wife and I would like to do some sightseeing today. Would you please introduce some places of historical interest in Beijing?
早上好。今天我太太和我想出去逛逛，你能给我们介绍一些北京的旅游景点吗？
服务员:
My pleasure， sir. Above all， I would recommend the Great Wall. It is amazing.
很荣幸，先生。我首先推荐长城。那是个神奇的地方。
客人:
I’ve heard of it for a long time.
我很久以前就听说了。

服务员:
Yes. As the saying goes/As an old saying goes， ‘He who has never been to the Great Wall is not a true man’.
是啊。俗话说/古语有云“不到长城非好汉！”
客人:
Great! Mary， let’s start off right now.
太棒了！Mary，我们现在就去。

as an old saying goes 可以译成：古人云......；有一句老话说......
用法如下：
As an old saying goes," opportunity is for the ready man".
俗话说“机遇总是给有准备的人”，“有备而战，战无不胜”。
希望能帮到你！！！

古语有云：。。。。

如一俗语说:
for example : As an old saying goes, you are not a hero untill you reached the Great Wall.

As the saying goes that…（As the prove says/goes that…） 俗话说…prove：俚语.用saying也可以,但如果用saying,后面最好用goes,免得says和saying一起出现不符合常理习惯.saying前有old可以理解为楼上所言“正如...

正如那句如何使用去

as an old saying goes, 后面加那句old saying即可。