What is the ruling on paying the dowry and establishing a home for marriage from the proceeds of a shop that sells beer? Is the saying "A void contract in corrupt lands is not forbidden" correct? And is the marriage valid in this case?

If beer is alcohol-free, then trading in it is permissible, and its price is lawful. However, if it contains an intoxicant, then trading in it is forbidden, and its price is ill-gotten gain, due to the warning of the Prophet (peace be upon him) concerning alcohol and those who deal with it. Repentance from unlawful gain is obligatory, and one must dispose of it by spending it on general Muslim interests with the intention of riddance, not charity. But if the earner is poor, it is permissible for him to take from it what suffices for his own needs and those of his family. Marriage is valid even if the dowry is from unlawful gain, provided that the conditions for validity are met.