An old saying goes, "When in Rome, do as the Romans do."

俗话说：“入乡随俗。”

youdao

As an old saying goes, "The rose is in her hand, the flavor in mine."

正如俗话所说的：“赠人玫瑰，手有余香。”

youdao

As the old saying goes, where there's a will, there's a way.

古话说，有志者事竟成。

《新英汉大辞典》

The experts agree with the old saying that you should never put anything smaller than your elbow in your ear.

VOA: special.2010.03.31

I think there's the old saying, "You can't run before you walk." and I think it's basically the same thing about writing.

有句俗话叫，“你不能未立先走。”我觉得写作跟这个是一个道理。

英语阅读：技巧 - SpeakingMax英语口语达人

Think about an eight year old girl, who's very unhappy, and then reads some magazine about that study, saying that basically you are genetically set point what you are born with is there for life.

设想一个8岁的女孩，她很忧伤，然后在杂志上读到那个研究，研究告诉她，基本上你的基因决定了一切,你与生俱来的一切，将伴随你终生。

哈佛公开课 - 幸福课课程节选

Remember the old saying "you have to love yourself before you can love someone else"?

FORBES: Readers Say

"There's an old saying that charity begins at home, but it cannot end there, " Rock said.

CNN: Telethon tries to raise 'Hope for Haiti'

As the old saying goes, the fact that you're paranoid doesn't mean you're not being followed.

ECONOMIST: Letters