‘Urwah narrated: “When the following verse was revealed:

(اسْتَغْفِرْ لَهُمْ أَوْ لَا تَسْتَغْفِرْ لَهُمْ إِن تَسْتَغْفِرْ لَهُمْ سَبْعِينَ مَرَّةً فَلَن يَغْفِرَ اللَّهُ لَهُمْ…) (Ask forgiveness for them, [Oh Muhammad], or do not ask forgiveness for them. Even if you should ask forgiveness for them seventy times – never will Allah forgive them.): The Prophet Muhammad (saws) said: “I will increase (my invocation for forgiveness) on their behalf to more than seventy times.” So, Allah revealed:

  سَوَاءٌ عَلَيْهِمْ أَسْتَغْفَرْتَ لَهُمْ أَمْ لَمْ تَسْتَغْفِرْ لَهُمْ لَن يَغْفِرَ اللَّهُ لَهُمْ ۚ إِنَّ اللَّهَ لَا يَهْدِي الْقَوْمَ الْفَاسِقِينَ 

(Whether you (Oh Muhammad) ask forgiveness for them or do not ask forgiveness for them, Allah will not forgive them. Indeed, Allah does not guide the defiantly disobedient people) (Al-Munafiqun: 6)

When Abdullah ibn Ubayy ibn Salul, the head of the hypocrites, passed away – (he was the one who incited against the Prophet Muhammad (saws) and said, “Do not spend on those who are with the Messenger of Allah until they disband,”; and was involved in the false accusation against ‘Aisha, the Mother of the Believers (may Allah be pleased with her)) – his son came to the Prophet Muhammad (saws) and said: “Ask forgiveness for my father,” meaning, seek forgiveness from Allah for him. The Prophet (saws) did seek forgiveness for him as an honor for Abdullah, his son, who had embraced Islam and proved good his faith. The the verse revealed:

(اسْتَغْفِرْ لَهُمْ أَوْ لَا تَسْتَغْفِرْ لَهُمْ إِن تَسْتَغْفِرْ لَهُمْ سَبْعِينَ مَرَّةً فَلَن يَغْفِرَ اللَّهُ لَهُمْ…) (Ask forgiveness for them, [Oh Muhammad], or do not ask forgiveness for them. Even if you should ask forgiveness for them seventy times – never will Allah forgive them.): The mention of the number seventy is meant to refer to great number, indicating that no matter how many times forgiveness is sought for them, Allah will not forgive them for their hypocrisy and disbelief, and for what they had done to His messenger (saws). The Prophet Muhammad (saws) used to seek forgiveness for his people, saying,

“Oh Allah, forgive my people, for they do not know.”[1]

However, Allah (swt) decreed that forgiveness would not be granted to them, stating, “never will Allah forgive them.”

…ذَٰلِكَ بِأَنَّهُمْ كَفَرُوا بِاللَّهِ وَرَسُولِهِ ۗ…  (That is because they disbelieved in Allah and His Messenger,): The fundamental reason is that they disbelieved in Allah (swt) and His Messenger, Muhammad (saws).

…وَاللَّهُ لَا يَهْدِي الْقَوْمَ الْفَاسِقِينَ (and Allah does not guide the defiantly disobedient people.): The hypocrite is a disobedient person because they violate the commands of Allah (swt).

[1] Sahih Bukhari: The Book of Prophets, Chapter no. 52, Hadith no. 3290