Here I will cover the positions of the two orthodox schools of theology in Islam, that of the Asha`ris and the Maturidis, on the subjects of predestination, reward, punishment, etc.
The Asha`ris place emphasis on the autonomy of God’s power and will, for when exercising His power and will, bringing something into being, He could simultaneously, not bring that something into being, and therefore His ordainment and decree (collectively known as predestination) are both contingent. The very definition of tyranny or opression, is infringing on the rights and property of others, but it is impossible for God to encounter any property other than His own, and therefore injustice cannot be attributed to Him who has absolute dominion and ownership over everything. Lastly, the actions of His creatures do not in any way harm Him nor do they benefit Him, therefore it is His prerogative to reward the obedient and punish the disobedient, not His obligation.
The Maturidis place emphasis on God’s foreknowledge and wisdom, and do not believe His ordainment and decree can be changed. The creature is granted a contingent power, which in itself inclines towards neither good nor evil. The universe and everything in it therefore, is like that of a river flowing towards its already existing destination; and any change in the universe is like a pebble being dropped into the river, creating no impediment to the river’s destination, and God knows all this. The Maturidis do not believe in the possibility of God punishing the obedient and rewarding the disobedient, because they believe everything God does is according to His wisdom, and cannot contravene His wisdom.
Ultimately, both schools believe that God does not punish the obedient and reward the disobedient, the Asha`ris may believe in its possibility according to God’s will, but they do not believe there can be any falsehood in God’s knowledge and speech (otherwise His knowledge and speech would be contingent and not necessary) i.e. lying is an impossibility for God. Predestination also, is a deep ocean, and even the most knowledgeable of theologians can drown if they go too deep. For having detailed knowledge of predestination would require having detailed knowledge of God’s specific operations, and we cannot know of these things except what God has disclosed to us. The issue in Islam, is therefore summarised as free will being zahir (apparent), for we are responsible for our actions, and predestination being batin (a hidden reality).
I hope this helped, please read also my posts on God’s existence when you have the time: