What should a wife do with her husband who uses hashish and does not pray, knowing that he treats her well and she does not want to expose him?

The man's statement that cannabis is a "gift" is an excuse worse than the sin itself. He is adding to his personal sin by aiding others in sin, and he bears the burden of those he misleads without knowledge. It has been authentically reported from the Prophet, peace and blessings be upon him: "And whoever introduces a bad practice in Islam will bear its sin and the sin of whoever acts upon it until the Day of Resurrection, without anything being diminished from their sins." More appalling than that is his abandonment of prayer, which is a grave sin. Indeed, some scholars have gone so far as to consider one who abandons prayer a disbeliever, while the majority hold him to be a fasiq (transgressor). This man must be advised and reminded of Allah. If he repents, then praise be to Allah. Otherwise, the wife should seek to separate from him by requesting a divorce, for it is the right of a woman to seek divorce due to the husband's transgression.