What does « What / That which » mean in the Quran?

And when it is said to them, "Do not cause corruption on the earth," they say, "We are but reformers."

And when it is said to them, "Believe as the people have believed," they say, "Should we believe as the foolish have believed?" Unquestionably, it is they who are the foolish, but they know [it] not.

And when they meet those who believe, they say, "We believe"; but when they are alone with their evil ones, they say, "Indeed, we are with you; we were only mockers."

Those are the ones who have purchased error [in exchange] for guidance, so their transaction has brought no profit, nor were they guided.

Their example is that of one who kindled a fire, but when it illuminated what was around him, Allah took away their light and left them in darkness [so] they could not see.

And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a surah the like thereof and call upon your witnesses other than Allah, if you should be truthful.

Indeed, Allah is not timid to present an example - that of a mosquito or what is smaller than it. And those who have believed know that it is the truth from their Lord. But as for those who disbelieve, they say, "What did Allah intend by this as an example?" He misleads many thereby and guides many thereby. And He misleads not except the defiantly disobedient,

Who break the covenant of Allah after contracting it and sever that which Allah has ordered to be joined and cause corruption on earth. It is those who are the losers.

It is He who created for you all of that which is on the earth. Then He directed Himself to the heaven, [His being above all creation], and made them seven heavens, and He is Knowing of all things.

And [mention, O Muhammad], when your Lord said to the angels, "Indeed, I will make upon the earth a successive authority." They said, "Will You place upon it one who causes corruption therein and sheds blood, while we declare Your praise and sanctify You?" Allah said, "Indeed, I know that which you do not know."

They said, "Exalted are You; we have no knowledge except what You have taught us. Indeed, it is You who is the Knowing, the Wise."

He said, "O Adam, inform them of their names." And when he had informed them of their names, He said, "Did I not tell you that I know the unseen [aspects] of the heavens and the earth? And I know what you reveal and what you have concealed."

But Satan caused them to slip out of it and removed them from that [condition] in which they had been. And We said, "Go down, [all of you], as enemies to one another, and you will have upon the earth a place of settlement and provision for a time."

And believe in what I have sent down confirming that which is [already] with you, and be not the first to disbelieve in it. And do not exchange My signs for a small price, and fear [only] Me.

And We shaded you with clouds and sent down to you manna and quails, [saying], "Eat from the good things with which We have provided you." And they wronged Us not - but they were [only] wronging themselves.

But those who wronged changed [those words] to a statement other than that which had been said to them, so We sent down upon those who wronged a punishment from the sky because they were defiantly disobeying.

And [recall] when you said, "O Moses, we can never endure one [kind of] food. So call upon your Lord to bring forth for us from the earth its green herbs and its cucumbers and its garlic and its lentils and its onions." [Moses] said, "Would you exchange what is better for what is less? Go into [any] settlement and indeed, you will have what you have asked." And they were covered with humiliation and poverty and returned with anger from Allah [upon them]. That was because they [repeatedly] disbelieved in the signs of Allah and killed the prophets without right. That was because they disobeyed and were [habitually] transgressing.

And [recall] when We took your covenant, [O Children of Israel, to abide by the Torah] and We raised over you the mount, [saying], "Take what We have given you with determination and remember what is in it that perhaps you may become righteous."

And We made it a deterrent punishment for those who were present and those who succeeded [them] and a lesson for those who fear Allah.

They said, "Call upon your Lord to make clear to us what it is." [Moses] said, "[Allah] says, 'It is a cow which is neither old nor virgin, but median between that,' so do what you are commanded."

They said, "Call upon your Lord to show us what is her color." He said, "He says, 'It is a yellow cow, bright in color - pleasing to the observers.' "

They said, "Call upon your Lord to make clear to us what it is. Indeed, [all] cows look alike to us. And indeed we, if Allah wills, will be guided."

He said, "He says, 'It is a cow neither trained to plow the earth nor to irrigate the field, one free from fault with no spot upon her.' " They said, "Now you have come with the truth." So they slaughtered her, but they could hardly do it.

And [recall] when you slew a man and disputed over it, but Allah was to bring out that which you were concealing.

Then your hearts became hardened after that, being like stones or even harder. For indeed, there are stones from which rivers burst forth, and there are some of them that split open and water comes out, and there are some of them that fall down for fear of Allah. And Allah is not unaware of what you do.