O you who believe! Al-Qisas (the Law of Equality in punishment) is prescribed for you in case of murder: the free for the free, the slave for the slave, and the female for the female. But if the killer is forgiven by the brother (or the relatives, etc.) of the killed against blood money, then adhering to it with fairness and payment of the blood money, to the heir should be made in fairness. This is an alleviation and a mercy from your Lord. So after this whoever transgresses the limits (i.e. kills the killer after taking the blood money), he shall have a painful torment.

So the Nafs (self) of the other (latter one) encouraged him and made fair-seeming to him the murder of his brother; he murdered him and became one of the losers.

Because of that We ordained for the Children of Israel that if anyone killed a person not in retaliation of murder, or (and) to spread mischief in the land - it would be as if he killed all mankind, and if anyone saved a life, it would be as if he saved the life of all mankind. And indeed, there came to them Our Messengers with clear proofs, evidences, and signs, even then after that many of them continued to exceed the limits (e.g. by doing oppression unjustly and exceeding beyond the limits set by Allah by committing the major sins) in the land!.

They swear by Allah that they said nothing (bad), but really they said the word of disbelief, and they disbelieved after accepting Islam, and they resolved that (plot to murder Prophet Muhammad ﷺ) which they were unable to carry out, and they could not find any cause to do so except that Allah and His Messenger had enriched them of His Bounty. If then they repent, it will be better for them, but if they turn away, Allah will punish them with a painful torment in this worldly life and in the Hereafter. And there is none for them on earth as a Wali (supporter, protector) or a helper.