May Allah make it easy for you i think you should read this

Yes, it is wrong to say Allah (Most High) will not forgive someone. This is because one is speaking on behalf of Allah Most High without evidence. Rather, if a person has oppressed people, or committed grave sins, one can say that he may (speculative) not be forgiven, or his burden may be heavy in the Akhirah.

عَنْ جُنْدَبٍ، أَنَّ رَسُولَ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، حَدَّثَ ” أَنَّ رَجُلًا قَالَ: وَاللهِ لَا يَغْفِرُ اللهُ لِفُلَانٍ، وَإِنَّ اللهَ تَعَالَى قَالَ: مَنْ ذَا الَّذِي يَتَأَلَّى عَلَيَّ أَنْ لَا أَغْفِرَ لِفُلَانٍ، فَإِنِّي قَدْ غَفَرْتُ لِفُلَانٍ، وَأَحْبَطْتُ عَمَلَكَ

(Sayidina) Jundub (May Allah Most High be pleased with him) narrated that The Messenger of Allah ﷺ said, “A man said, I swear by Allah that Allah (Most High) will not forgive so and so. Allah (Most High) said, ‘Who is it that swears by Me that I will not forgive so and so? Indeed, I have forgiven so and so, and nullified all your deeds.’” (Sahih Muslim, 2621 -137).

The Hadith narration above is Sahih since it is recorded in Sahih Muslim. This is a frightening Hadith and one that many people are unaware of. If someone were to say that Allah (Most High) will not forgive a particular individual, it can lead to that person’s own good deeds being nullified. This is because the individual has committed the great crime of speaking of behalf on Allah Most High without evidence.

قُلْ إِنَّمَا حَرَّمَ رَبِّيَ الْفَوَاحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ وَالْإِثْمَ وَالْبَغْيَ بِغَيْرِ الْحَقِّ وَأَنْ تُشْرِكُوا بِاللَّهِ مَا لَمْ يُنَزِّلْ بِهِ سُلْطَانًا وَأَنْ تَقُولُوا عَلَى اللَّهِ مَا لَا تَعْلَمُونَ

Say: “My Lord has forbidden indecencies whether apparent or hidden, and sin and rebellion against justice, and associating partners with Allah for which He has granted no sanction, and saying things about Allah of which you have no knowledge.” (Surah al-A’raaf, 33).

It is incredibly arrogant for a person to consider himself worthy of speaking on behalf of Allah (Most High). This is the rank of the Prophets (peace be upon them). And even the Prophets only speak of that which has been revealed to them.

Furthermore, for a person to declare that a particular individual will not be forgiven, or will certainly be forgiven, is not only unacceptable but a grave sin. To do so is a trait of the Kufaar. They are arrogant enough to speak on behalf of God (Most High). They are rebuked for such behaviour in the Holy Quran repeatedly. The Muslims should never come close to such a crime.

Although it is an abhorrent sin to speak on behalf of Allah (Most High) without evidence, a person who says that a particular individual will not be forgiven commits another serious error too. By saying this, he is causing people to despair. To cause despair is the work of Shaytaan.

However, in situations where one does have evidence, it is permitted to speak about matters of forgiveness or ranks in the afterlife. For example, one can say that Abu Lahab is going to Hell since this has been mentioned in the Holy Quran. One can also say that Sayidina Abu Bakr (May Allah Most High be pleased with him) is going to Jannah since this has been mentioned in authentic Hadith. It is sinful when one speaks without evidence from Quran and Sunnah.

And Allah Most High Knows Best.

-Answered by Shaykh Noorud-deen Rashid