What is the ruling on using cannabis while maintaining prayer, knowing that the addict is trying to quit it and sees it as similar to smoking?

It is obligatory to hasten to repent to Allah from drug use, because it is forbidden and among the gravest of forbidden acts. Do not delay repentance, and beware of Satan's discouragement, for repentance is easy, by Allah's permission. And beware of Satan discouraging you from maintaining prayer because of your involvement in this evil, for prayer is the pillar of Islam, the key to all good, and it is sought for help in every matter. Allah Almighty said: "And seek help through patience and prayer, and indeed, it is difficult except for the humbly submissive [to Allah]."