123. And tfius We Jiaue set up in every town great ones of its wicked people to plot therein. But they plot not except against themselves, and they perceive (it) not.
124. And when there comes to them a sign they say: "We shall not believe until we receive the like of that which the Messengers of Allah received." Allah knows best with whom to entrust His Message. Humiliation and disgrace from Allah and a severe torment will overtake the criminals for that which they used to plot.

Allah says: Just as We appointed chiefs and leaders for the criminals who call to disbelief, hinder from the path of Allah, and oppose and defy you in your town, O Muhammad. Such was also the case with the Messengers before you, who were tested with the same. But the good end was always theirs.’ Allah said in other Ayat,

Thus have We made for every Prophet an enemy among the criminals.} [25:31]

Allah said,

And when We decide to destroy a town, We send a definite order to those among them who lead a life of luxury, and they transgress therein.} [17:16]

meaning, We command them to obey Us, but they defy the command and as a consequence, We destroy them. It was also said that, “We send a definite order”, in the last Ayah means, “We decree for them,” as Allah stated here

to plot therein.}

Ibn Abi Talhah reported that Ibn ‘Abb§s explained the Ayah

...great ones of its wicked people to plot therein.}

“We give the leadership to these wicked ones and they commit evil in it. When they do this, We destroy them with Our torment.”

Mujahid and Qatadah said that in the Ayah,

great ones} refers to leaders. I say that this is also the meaning of Allah’s statements,

And We did not send a wamer to a township, but those who were given the worldly wealth and luxuries among them, said: "We believe not in what you have been sent with." And they say : "We have too much wealth and too many children and we are not going to suffer punishment ."} [34:34-35]

And,

And similarly. We sent not a wamer before you to any town but the luxurious ones among them said: "We found our fathers following a certain way and religion, and we will indeed follow their footsteps."} [43:23]

'Plot’ in the Ayah [6:123] refers to beautified speech and various actions with which the evil ones call to misguidance. Allah said about the people of Prophet Nuh, peace be upon him,

They have plotted a mighty plot.} (71:22)

Allah said,

But if you could see when the wrongdoers will be made to stand before their Lord, how they will cast the (blaming) word one to another! Those who were deemed weak will say to those who were arrogant: “ Had it not been for you, we should certainly have been believers." And those who were arrogant will say to those who were deemed weak: ", Did we keep you back from guidance after it had come to you? Nay, but you were criminals." Those who were deemed weak will say to those who were arrogant: "Nay, but it was your plotting by night and day, when you ordered us to disbelieve in Allah and set up rivals for Him!"} (34:31-33).

Ibn Abi Hatim reported that Ibn Abi 'Umar said that Sufyan said, “Every “plot’ mentioned in the Qur’an refers to actions.” Allah’s statement,

But they plot not except against themselves, and they perceive (it) not.}

means, the harm of their wicked plots, as well as misguiding those whom they lead astray, will only strike them. Allah said in other Ay&t,

And verily, they shall bear their own loads, and other loads besides their own.} (29:13) and,

That they may bear their own burdens in full on the Day of Resurrection, and also of the burdens of those whom they misled without knowledge. Evil indeed is that which they shall bear!} (16:25)

transgression, rebellion and defiance. Allah described them,

And when they see you, they only mock: "Is this the one whom Allah has sent as a Messenger ?"} [25:41] and

And when those who disbelieved see you, they only mock at you : "Is this the one who talks about your gods?" While they disbelieve at the mention of the Most Gracious (Allah).} [21:36], and,

Indeed Messengers were mocked before, but the scoffers were surrounded by that, whereat they used to mock.} [21:41]

The Disbelievers Admit to the Prophet’s Nobility of Lineage

The disbelievers did all of this although they admitted to the Prophet’s virtue, honorable lineage, respectable ancestry and purity of household and upbringing, may Allah, His angels, and the believers send blessings upon him. The disbelievers used to call the Prophet, before he received revelation, ‘Al-Amin’ - the Truthful. The leader of the Quraysh disbelievers, Abu Sufyan, had to admit to this fact when Heraclius, emperor of Rome, asked him, “How honorable is his (the Prophet’s) ancestral lineage among you?” Abu Sufyan answered, “His ancestry is highly regarded among us.” Heraclius asked, “Do you find that he lied, before he started his mission?" Abu Sufyan replied, “No.” The emperor of Rome relied on the honor and purity of the Prophet to recognize the truth of his prophethood and what he came with.

Imam Ahmad recorded that Wathilah bin Al-Asqa‘ said that the Messenger of Allah said,

And your Lord treats no one with injustice} [18:49]

Allah said in another Ayah,

The Day when all the secrets will be examined .} [86:9]

Meaning, the secrets, hidden thoughts and intentions will be exposed.

In the Two SahVis, it is recorded that the Messenger of Allah said,

«A banner will be raised for every deceitful person from his anus on the Day of Resurrection, and it will say; 'This is the treacherous plot of so-and-so, son of so-and-so, son of so-and-so.'»

The wisdom in this is that since a plot occurs in secret, and people are usually unaware of it, then on the Day of Resurrection the plot itself will become public news testifying to the actions of those who committed it.