Is the buyer obligated to pay for beer to the merchant's heirs after the merchant repents from selling it, or is the contract void and he is not obligated to pay?

Intoxicating beer is forbidden, and so is trading in it, based on the Prophet's (PBUH) saying: "Indeed, Allah Almighty, when He forbids the eating of something, He forbids its price." And his saying: "Indeed, Allah and His Messenger have forbidden the sale of intoxicants, dead animals, swine, and idols." And his saying: "Every intoxicant is forbidden."

Therefore, the heirs have no right to the price of intoxicating beer from the buyer.

As for the money earned by the seller from selling intoxicating beer, he must dispose of it for the general welfare of Muslims or for the poor and needy, because this money is illicit due to its unlawful earning. It should not be returned to its owner because he expended it by his own choice and received its forbidden compensation.