What is the ruling of Islamic law concerning the profits from a café frequented by men and women mixing, given that restrictions are imposed on employees to prevent the sale of forbidden items and to avoid indecent practices?

The owner has done well by prohibiting the sale of forbidden substances, cigarettes, and immoral practices. However, he must also prevent mixing (of genders) due to the evil, corruption, and temptation it entails. Religious texts have indicated the prohibition of mixing, such as the Almighty's saying: (And when you ask [his wives] for something, ask them from behind a partition. That is purer for your hearts and their hearts), and His saying: (O wives of the Prophet, you are not like anyone among women. If you fear Allah, then do not be soft in speech [to men] lest he in whose heart is disease should covet, but speak with appropriate speech). Similarly, the Prophet (peace be upon him) observed the prevention of mixing in mosques by separating the rows, staying after the salutations until the women departed, dedicating a special door for women, and also commanding women to walk on the edges of the road. The cafe owner is sinful by condoning mixing, and he must fear Allah and prevent mixing, or restrict the cafe to men only. Otherwise, he should seek another permissible job, for whoever gives up something for the sake of Allah, Allah will compensate him with something better.