They ask thee concerning fighting in the Prohibited Month. Say: "Fighting therein is a grave (offence); but graver is it in the sight of God to prevent access to the path of God, to deny Him, to prevent access to the Sacred Mosque, and drive out its members." Tumult and oppression are worse than slaughter. Nor will they cease fighting you until they turn you back from your faith if they can. And if any of you Turn back from their faith and die in unbelief, their works will bear no fruit in this life and in the Hereafter; they will be companions of the Fire and will abide therein. (2:217)

They swear by God that they said nothing (evil), but indeed they uttered blasphemy, and they did it after accepting Islam; and they meditated a plot which they were unable to carry out: this revenge of theirs was (their) only return for the bounty with which God and His Apostle had enriched them! If they repent, it will be best for them; but if they turn back (to their evil ways), God will punish them with a grievous penalty in this life and in the Hereafter: They shall have none on earth to protect or help them. (9:74)