my friend's husband has a halal restaurant where they allow people to bring their own alcohol but do not sell alcohol. can i accept gifts or food from them?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is impermissible for your friend’s husband to allow customers to drink alcohol in his restaurant even if he does not sell it himself. His wife should make that clear to him that it is impermissible for him to allow customers to drink alcohol, the mother of all evils, in his restaurant. If he does not prohibit and prevent those customers from drinking alcohol in his restaurant, then he is sinful.

However, this does not render his earnings from serving lawful food in the restaurant unlawful. Hence, there is no harm in accepting gifts from his money or food, whether they are offered by him or his wife.

Allaah Knows best.