Is Allah Almighty capable of producing words better than the Qur’an, or a law more perfect than the law of Islam?

You must believe that Allah is capable of all things, and that you should cast away whispers (waswas). The saying of Al-Ghazali: "There is nothing more perfect possible than what was," has been rejected by many scholars, and some have offered excuses for it. Sheikh al-Islam Ibn Taymiyyah held that this statement is incorrect if it means that Allah is unable to do anything other than what He has done. However, if it means that what Allah has done is the best and most complete, then this is not a deficiency in His capability, but rather a description of Allah's generosity, munificence, and benevolence. In summary: what Allah has done and legislated is a manifestation of His mercy and profound wisdom, and you should not preoccupy yourself with whispers.