Are the parents of the Prophet (peace and blessings of Allah be upon him) in Paradise or in Hell?
Question

Where are the parents of the Prophet (peace and blessings of Allah be upon him)? Are they in Paradise or in Hell? We hope you can tell us of a hadith which proves the answer?.
Praise be to Allah.There is a hadith from the Prophet (peace and blessings of Allah be upon him) which indicates that they are in Hell. 
Muslim (203) narrated from Anas (may Allah be pleased with him) that a man said: “O Messenger of Allah, where is my father?” He said: “In Hell.” When he turned away he called him back and said: “My father and your father are in Hell.” 
Al-Nawawi (may Allah have mercy on him) said: 
This shows that whoever dies in a state of kufr will be in Hell. And being related to one who is close to Allah will not avail him anything. It also shows that whoever died during the fatrah (the interval between the Prophethood of ‘Eesa (peace be upon him) and that of Muhammad (peace and blessings of Allah be upon him)) and was the follower of the way of the Arabs at that time, which was idol worship, will also be among the people of Hell. There is no excuse for the call not reaching them, because the call of Ibraaheem and other Prophets (peace be upon them) had reached these people. 
Muslim (976) narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “I asked my Lord for permission to pray for forgiveness for my mother, but He did not give me permission. And I asked Him for permission to visit her grave, and He gave me permission.” 
It says in ‘Awn al-Ma’bood: 
“But He did not give me permission” means: because she was a kaafirah (disbeliever) and it is not permissible to pray for forgiveness for the kuffaar. 
Al-Nawawi (may Allah have mercy on him) said: 
This shows that it is not permitted to pray for forgiveness for the kuffaar. 
Shaykh Ibn Baaz (may Allah have mercy on him) said: 
When the Prophet (peace and blessings of Allah be upon him) said, “My father and your father are in Hell,” he spoke with knowledge, for he did not speak on the basis of his whims and desires, as Allah says (interpretation of the meaning):
“By the star when it goes down (or vanishes).
2. Your companion (Muhammad) has neither gone astray nor has erred.
3. Nor does he speak of (his own) desire.
4. It is only a Revelation revealed”
[al-Najm 53:1-4]
Were it not that proof has been established against ‘Abd-Allah ibn ‘Abd al-Muttalib, the father of the Prophet (peace and blessings of Allah be upon him), the Prophet (peace and blessings of Allah be upon him) would not have said what he did about him. Perhaps he had heard something that established proof against him on the basis of the religion of Ibraaheem, because they used to follow the religion of Ibraaheem until the innovations were introduced by ‘Amr ibn Luhayy al-Khuzaa’i and his innovations became widespread among the people, such as the propagation of idols and praying to them instead of to Allah. Perhaps ‘Abd-Allah had heard something that showed him that the idol worship of Quraysh was wrong, but he still followed them, and thus proof was established against him. Similarly, the hadith which says that the Prophet (peace and blessings of Allah be upon him) asked for permission to pray for forgiveness for his mother but it was not granted, and he asked for permission to visit her grave and he was permitted to do so but not to pray for forgiveness for her, perhaps she had heard something that established proof against her, or perhaps the people of the Jaahiliyyah are to be treated as kuffaar as far as rulings in this world are concerned, so we should not pray for them or pray for forgiveness for them, because outwardly they seem to be kuffaar, and should be regarded and dealt with as such, and their case in the Hereafter is for Allah to judge. 
Fatawa Noor ‘ala al-Darb 
Al-Suyooti (may Allah have mercy on him) was of the view that the parents of the Prophet (peace and blessings of Allah be upon him) will be saved (from Hell), and that Allah brought them back to life after they had died and they believed in him. 
This view was rejected by the majority of scholars who ruled that the ahaadith which indicate that are fabricated (mawdoo’) or very weak (da’eef jiddan). 
It says in ‘Awn al-Ma’bood: 
Most of the reports that been narrated to the effect that the parents of the Prophet (peace and blessings of Allah be upon him) were brought back to life and believed in him and were saved are fabricated and false. Some of them are very weak and cannot be saheeh under any circumstances, as the imams of hadith are unanimously agreed that they are fabricated, such as al-Daaraqutni, al-Jawzaqaani, Ibn Shaheen, al-Khateeb, Ibn ‘Asaakir, Ibn Naasir, Ibn al-Jawzi, al-Suhayli, al-Qurtubi, al-Muhibb, al-Tabari, Fath al-Deen ibn Sayyid al-Naas, Ibraaheem al-Halabi and others. The scholar Ibraaheem al-Halabi explained at length the fact that the parents of the Prophet (peace and blessings of Allah be upon him) have not been saved from Hell in a separate essay, as did ‘Ali al-Qaari in Sharh al-Fiqh al-Akbar and in a separate essay. The basis for this opinion is the  soundness of this hadith (“My father and your father are in Hell”). Shaykh Jalaal al-Deen al-Suyooti differed from the huffaaz and scholars and affirmed that they had believed and had been saved, and he wrote numerous essays on that topic, including al-Ta’zeem wa’l-Minnah fi anna Abaway Rasool-Illaah (peace and blessings of Allah be upon him) fi’l-Jannah. 
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) was asked: Is there any saheeh report from the Prophet (peace and blessings of Allah be upon him) that Allah brought his parents back to life so that they could become Muslims, then they died (again) after that? 
He replied: There is no saheeh report to that effect from the scholars of hadith. Rather the scholars are agreed that this is an invented lie… There is no dispute among the scholars that this is one of the most obvious of fabrications, as was stated by those who have knowledge. That does not appear in any of the reliable books of hadith, either in the Saheehs or the Sunans or the Musnads or any other well-known books of hadith. It was not mentioned by the authors of the books of Maghaazi or Tafseer, even though they narrated da’eef (weak) reports along with saheeh (sound) ones. The fact that this is a lie is clear to any one who has any knowledge of religion. If such a thing had happened there would have been a great deal of motivation to transmit it, because it is something that is extraordinary on two counts: the raising of the dead and believing after death. Such a thing would have been more deserving of being transmitted than anything else. Since no trustworthy narrated transmitted it, it may be understood that this is a lie. 
Moreover, this goes against the Qur’aan and the saheeh Sunnah, and the consensus of the scholars. Allah says (interpretation of the meaning): 
“Allah accepts only the repentance of those who do evil in ignorance and foolishness and repent soon afterwards; it is they whom Allah will forgive and Allah is Ever All‑Knower, All‑Wise.
18. And of no effect is the repentance of those who continue to do evil deeds until death faces one of them and he says: ‘Now I repent;’ nor of those who die while they are disbelievers”
[al-Nisa’ 4:17-18]
So Allah states that there is no repentance for one who dies as a disbeliever. And Allah says (interpretation of the meaning): 
“Then their Faith (in Islamic Monotheism) could not avail them when they saw Our punishment. (Like) this has been the way of Allah in dealing with His slaves. And there the disbelievers lost utterly (when Our Torment covered them)”
[Ghaafir 40:85]
 So He tells us that the way in which He deals with His slaves is that faith will be to no avail once they have seen the punishment, so how about after death? And there are other similar texts. Then he quoted the two hadith which we quoted at the beginning of our answer. 
Majmoo’ al-Fatawa, 4/325-327.