The Family Of Imran - 3:8 Our Lord, do not let our hearts be perverted after you have guided us to the truth. Shower upon us Your mercy; surely You are the Forgiving.
Whoever disbelieves after believing:
The Family Of Imran/3:90 The repentance of those who disbelieved after their belief and went further in their disbelief will not be accepted; they have gone astray.
The Family Of Imran/3:91 Those who disbelieve and die as disbelievers will not be accepted from them even if they give the world´s gold as ransom. They have deserved a painful torment and they will have no helpers.

The Cow/2:161 And those who disbelieve and die as disbelievers will earn the curse of Allah, the angels and the people.
The Cow/2:162 They will remain in that state forever. Their torment will not be lightened nor will it be postponed.

The Family Of Imran/3:106 "On that Day some faces will be justified and some faces will be darkened. Those whose faces will be darkened will be told: "Did you disbelieve after you believed? Taste the torment for your disbelief."

The Women/4:137 Those who believe and then disbelieve, and believe again and then disbelieve again, and then go further in their disbelief, Allah will not forgive them nor guide them.

The Table Spread/5:12 "Allah had taken a promise from the Children of Israel and We sent twelve leaders from among them. Allah said: "I am with you if you observe the prayer, pay the zakat, believe in My messengers and respect them, and lend to Allah a good debt. I will cover your sins and give you gardens in which rivers flow. So whoever of you disbelieves after that has gone astray from the right path."
The Table Spread/5:114 "Jesus son of Mary: "Our God, our Lord, send down to us a banquet from heaven, so that it may be a feast for each of us and for all of us, and a proof from You. Provide for us. You are the best provider."
The Table Spread/5:115 "Allah said: "I will send it down to you,"He said: "Whoever disbelieves after that, I will punish him with a torment which I have never given to anyone."

The Repentance/9:65 "If you ask them, they will say: "We were only joking and playing". Say: "Do you mock Allah and His signs and His messenger?"
The Repentance/9:66 Do not apologize. You disbelieved after you believed. Even if We forgive some of you, We will punish some of you for their crime.
The Repentance/9:74 Although they speak words of disbelief and disbelieve after they have surrendered, they swear by Allah that they did not say them. In fact, they strived hard for what they could never attain. They sought revenge after Allah and His messenger had enriched them with His grace! It would be good for them if they repent. If they turn away, Allah will punish them with a painful torment in this world and in the Hereafter, and they will have neither friends nor helpers in the earth.

The Heights/7:89 "If we return to it after Allah has delivered us from your religion, we would be ascribing a lie to Allah. We cannot return to it unless Allah, our Lord, wills it. Our Lord encompasses all things with His knowledge. We put our trust in Allah alone. Set between us and our people with the truth, O our Lord. You are the best of revealers.

The Bee/16:106 Those who disbelieve in Allah and open their hearts to disbelief after faith, except those whose hearts are full of faith but are forced to disbelieve, have deserved wrath from Allah and for them is a painful torment.

Muhammad/47:1 Those who disbelieve and turn away from the way of Allah, He makes void all their deeds.
Muhammad/47:32 Those who disbelieve and turn away from the way of Allah and those who disobey the messenger after the right path has become clear to them can do Allah no harm. Rather, He will nullify their deeds.

The Hypocrites/63:1 "When the hypocrites come to you, they say, "We bear witness that you are the messenger of Allah. Allah knows that you are His messenger, and Allah testifies that the hypocrites lie."
The Hypocrites/63:2 They take their oaths as a shield and lead astray from the way of Allah. How evil is what they do.
The Hypocrites/63:3 Because they disbelieved after they believed, so their hearts were sealed; they do not understand.