How can a human being be given free will and not predestined, when their sustenance, their misery, their happiness, and everything that will befall them has been written for them while they were in their mother's womb?

Everything that occurs in the universe happens by Allah's divine decree (qada'), preordainment (qadar), and eternal knowledge. Everything Allah created was brought into existence with measure. Every calamity is predestined before its creation. Allah inscribed the destinies of all creatures fifty thousand years before He created them, and the first thing He created was the Pen, commanding it to write the destinies of everything. The actions of servants are all predetermined before their birth, yet Allah has granted the servant a choice, will, and intention, by which they choose the path of good or evil. They are held accountable for the actions they chose, for choice, coupled with reason and absence of coercion, is the basis of accountability. Allah is the Creator of the servants' actions. Allah Almighty says: "And Allah created you and that which you do" (Quran 37:96), and "And you do not will except that Allah wills" (Quran 76:30). This proves that servants have actions and a will, both of which are Allah's creation. The servant is held accountable and recompensed for their actions and will, which they perform by their choice. Allah has bestowed upon humans will, intention, capability, and choice, and has instilled in them the capacity for both good and evil. Humans are neither entirely compelled (musayyar) nor entirely free to choose (mukhayyar); rather, they are both mukhayyar and musayyar. They are mukhayyar because Allah has granted them reason, perception, and will to distinguish between good and evil, and thereby religious obligations become incumbent upon them. They are musayyar because their actions do not fall outside Allah's power and will. One must act and not rely solely on destiny, for everyone is facilitated for that for which they were created. Humans distinguish between voluntary and involuntary actions, and they act by their choice, and Allah observes them and recompenses them for their actions. One should avoid delving deeply into the subject of divine decree.