Allah will join the believer with his descendants in Paradise — even if they are not equal in good deeds!

وَالَّذِينَ آمَنُوا وَاتَّبَعَتْهُمْ ذُرِّيَّتُهُم بِإِيمَانٍ أَلْحَقْنَا بِهِمْ ذُرِّيَّتَهُمْ وَمَا أَلَتْنَاهُم مِّنْ عَمَلِهِم مِّن شَيْءٍ ۚ

“And those who believed and whose descendants followed them in faith — We will join them with their descendants, and We will not deprive them of anything from their deeds.”

(Quran 52:21)

Allah will join the believer with his descendants in Paradise — even if they are not equal in good deeds! As-Sa’di says in his Tafsir of this ayah:

وهذا من تمام نعيم أهل الجنة، أن ألحق الله [بهم] ذريتهم الذين اتبعوهم بإيمان أي: الذين لحقوهم بالإيمان الصادر من آبائهم، فصارت الذرية تبعا لهم بالإيمان،

“From the perfection of blessings for the people of Paradise is that Allah will join them with their descendants who followed them in emaan (belief in Allah). They followed them in belief because their fathers/forefathers (believed), and so they followed them.

‎فهؤلاء المذكورون، يلحقهم الله بمنازل آبائهم في الجنة وإن لم يبلغوها، جزاء لآبائهم، وزيادة في ثوابهم، ومع ذلك، لا ينقص الله الآباء من أعمالهم شيئا

Allah will allow these descendants to be with their forefathers in Paradise, even if their deeds were not sufficient to reach (the level of their forefathers) — as an added reward for their forefathers. Even though (the descendants may go up levels to join their forefathers), Allah will not reduce the good deeds of the forefathers at all.”