How can someone addicted to smoking and hashish, who nevertheless maintains prayer and reading the Quran, rid himself of his addiction?

You should praise Allah for the success in performing prayers and persevering in them, as it is an important step towards abandoning forbidden acts. Maintain the establishment of prayer with its conditions, pillars, and devotion, and frequently engage in the remembrance of Allah, supplicating to Him, and reciting His Book with reflection, for this is one of the greatest means of desisting from sins and transgressions. Allah Almighty says: "And establish prayer. Indeed, prayer prohibits immorality and wrongdoing, and the remembrance of Allah is greater. And Allah knows that which you do." (Al-Ankabut: 45). It is also advisable to contact clinics that assist smokers and addicts to benefit from their expertise in quitting these harmful and forbidden habits.