Evil is that for which they have sold their souls-- that they should deny what Allah has revealed, out of envy that Allah should send down of His grace on whomsoever of His servants He pleases; so they have made themselves deserving of wrath upon wrath, and there is a disgraceful punishment for the unbelievers.

And they followed what the Shaitans chanted of sorcery in the reign of Sulaiman, and Sulaiman was not an unbeliever, but the Shaitans disbelieved, they taught men sorcery and that was sent down to the two angels at Babel, Harut and Marut, yet these two taught no man until they had said, "Surely we are only a trial, therefore do not be a disbeliever." Even then men learned from these two, magic by which they might cause a separation between a man and his wife; and they cannot hurt with it any one except with Allah's permission, and they learned what harmed them and did not profit them, and certainly they know that he who bought it should have no share of good in the hereafter and evil was the price for which they sold their souls, had they but known this.

And among men is he who sells himself to seek the pleasure of Allah; and Allah is Affectionate to the servants.

Surely Allah has bought of the believers their persons and their property for this, that they shall have the garden; they fight in Allah's way, so they slay and are slain; a promise which is binding on Him in the Taurat and the Injeel and the Quran; and who is more faithful to his covenant than Allah? Rejoice therefore in the pledge which you have made; and that is the mighty achievement.