What is the ruling on cultivating Indian hemp and benefiting from it on inherited land, and what is the role of uncles and grandchildren in stopping this exploitation?

Cannabis is the source of the intoxicating hashish. Its consumption, cultivation, and trade are forbidden. Indeed, condoning a sin is a sin itself. Jurists have mentioned numerous religious and worldly harms associated with hashish. In some respects, it is even more harmful than alcohol, and it is difficult to quit. The money generated from its trade is illicit.

Therefore, it is impermissible to lease land to someone who cultivates this evil plant. You must advise your father and uncles to reclaim the land from the tenant, seeking legal assistance if necessary.