Suuratul – Ankabuut Verse 6.
وَمَن جَـٰهَدَ فَإِنَّمَا يُجَـٰهِدُ لِنَفْسِهِۦٓ ۚ إِنَّ ٱللَّـهَ لَغَنِىٌّ عَنِ ٱلْعَـٰلَمِينَ ﴿٦
6. And whosoever strives, he strives only for himself. Verily, Allah is free of all wants from the ‘Alamin (mankind, jinns, and all that exists).
Tafsir Ibn Kathir Volume 7, Page 460.
﴿وَمَن جَاهَدَ فَإِنَّمَا يُجَـهِدُ لِنَفْسِهِ﴾
(And whosoever strives, he strives only for himself.) This is like the Ayah,
﴿مَّنْ عَمِلَ صَـلِحاً فَلِنَفْسِهِ﴾
(Whosoever does righteous good deed, it is for himself) (41:46). Whoever does a righteous deed, the benefit of that deed will come back to him, for Allah has no need of the deeds of His servants, and even if all of them were to be as pious as the most pious man among them, that would not add to His dominion in the slightest. Allah says:
﴿وَمَن جَاهَدَ فَإِنَّمَا يُجَـهِدُ لِنَفْسِهِ إِنَّ اللَّهَ لَغَنِىٌّ عَنِ الْعَـلَمِينَ ﴾
(And whosoever strives, he strives only for himself. Verily, Allah stands not in need of any of the creatures.) Then Allah tells us that even though He has no need of His creatures, He is kind and generous to them. He will still give to those who believe and do righteous deeds the best of rewards, which is that He will expiate for them their bad deeds, and will reward them according to the best deeds that they did. He will accept the fewest good deeds and in return for one good deed will give anything between ten rewards and seven hundred, but for every bad deed, He will give only one evil merit, or even that He may overlook and forgive.