Well, you know what they say. A new broom sweeps clean.

唉，你知道他们说什么。新官上任三把火。

《牛津词典》

If they prove that I was wrong, then I'll go by what they say.

如果他们证明我错了，那么我就会照他们说的去做。

《柯林斯英汉双解大词典》

You have to hear what they say.

你得多听他们是怎么说的。

youdao

Conservatives object to the cost, and the idea of what they say is just another bailout for the car industry.

VOA: special.2009.08.07

They can pretty much pack it up and go home, because everyone's going to think they're ridiculous, no one will believe what they say, and it's a stupid idea anyway, is basically the gist of this conversation.

他们就可以打包回家了，因为每个人都会认为他们很荒谬，没有人会相信他们的说法，这是个很愚蠢的想法，这就是他们当时谈话的大概意思。

麻省理工公开课 - 化学原理课程节选

I don't agree with anything they do or what they say.

我绝不赞成他们所做的和他们所说的。

英国的极右政党 - SpeakingMax英语口语达人

Public figures have to choose carefully what they say because it will often come up again.

FORBES: Maine Women Sprout A #LittleBeard To Send BPA Message To Governor Paul LePage

Lay down a firm rule that statutes say what they mean and mean what they say.

FORBES: Why Justice Breyer Should Steer Clear of Political Science

Scores of Rohingyas have fled what they say is persecution in Burma in recent months.

BBC: Burma communal rioting spreads outside Meiktila