Prophet Jonah - 10:28
"On the Day when We gather them together, We will separate them from each other, saying to those who associate partners, "You and your partners, take your places!"And their associates will say: "You were not serving Us"."
Why does Allah not forgive those who die associating partners?
The Women/4:48
Allah does not forgive associating partners with Him, but other than that He forgives to whom He wills. Whoever associates partners with Allah has committed a great insult.
اِنَّ اللّٰهَ لَا يَغْفِرُ اَنْ يُشْرَكَ بِه۪ وَيَغْفِرُ مَا دُونَ ذٰلِكَ لِمَنْ يَشَٓاءُۚ وَمَنْ يُشْرِكْ بِاللّٰهِ فَقَدِ افْتَرٰٓى اِثْماً عَظ۪يماً
The Women/4:116
Allah does not forgive associating partners with Him (if it continues until death), but He forgives the sins below that to whom He wills. Whoever associates partners with Allah has gone astray.
اِنَّ اللّٰهَ لَا يَغْفِرُ اَنْ يُشْرَكَ بِه۪ وَيَغْفِرُ مَا دُونَ ذٰلِكَ لِمَنْ يَشَٓاءُۜ وَمَنْ يُشْرِكْ بِاللّٰهِ فَقَدْ ضَلَّ ضَلَالاً بَع۪يداً
Luqman/31:13
"When Lokman advised his son, he said: "My dear son, do not associate partners with Allah; surely shirk (associating partners with God) is a great wrong."
وَاِذْ قَالَ لُقْمٰنُ لِابْنِه۪ وَهُوَ يَعِظُهُ يَا بُنَيَّ لَا تُشْرِكْ بِاللّٰهِۜ اِنَّ الشِّرْكَ لَظُلْمٌ عَظ۪يمٌ
The Companies/39:65
It has been revealed to you and those before you that if you associate partners, all that you do will be in vain and you will be of the losers.
وَلَقَدْ اُو۫حِيَ اِلَيْكَ وَاِلَى الَّذ۪ينَ مِنْ قَبْلِكَۚ لَئِنْ اَشْرَكْتَ لَيَحْبَطَنَّ عَمَلُكَ وَلَتَكُونَنَّ مِنَ الْخَاسِر۪ينَ