Allah affirms His perfect justice and fairness in His decisions, for He decided that He will not change a bounty that He has granted someone, except on account of an evil that they committed. Allah said in another Ayah,

إِنَّ اللَّهَ لاَ يُغَيِّرُ مَا بِقَوْمٍ حَتَّى يُغَيِّرُواْ مَا بِأَنفُسِهِمْ وَإِذَآ أَرَادَ اللَّهُ بِقَوْمٍ سُوءًا فَلاَ مَرَدَّ لَهُ وَمَا لَهُمْ مِّن دُونِهِ مِن وَالٍ

(Verily, Allah will not change the (good) condition of a people as long as they do not change their state (of goodness) themselves. But when Allah wills a people's punishment, there can be no turning it back, and they will find besides Him no protector.) 13:11

Stated in the fourth verse (53) there is a standing rule which spells out the condition under which Allah Ta` ala allows a people to continue enjoying blessings bestowed by Him. It was said: بِأَنَّ اللَّـهَ لَمْ يَكُ مُغَيِّرً‌ا نِّعْمَةً أَنْعَمَهَا عَلَىٰ قَوْمٍ حَتَّىٰ يُغَيِّرُ‌وا مَا بِأَنفُسِهِمْ (because Allah is not to change a favour He has conferred on a people unless they change their own selves - 53).

The first thing worth pondering about at this place is that Allah Ta` ala has not set forth any rule as to the bestowal of blessing and favour, nor has He put any restriction and condition for it, nor has He made it to be dependent on some good deed - because, had this been so, then, the foremost favour bestowed on us is our very existence. Placed in this marvelous menagerie of the power of Allah are thousands and thousands of additional blessings which, it is all too obvious, were conferred on us at a time when we did not exist nor any of our deed did.