Ruling on renting out a hall to someone who will hold a mixed party there

It is not permissible to rent out halls to those who will hold parties that involve sinful things, such as mixing between men and women, or haraam music and other sins, because Allaah says (interpretation of the meaning): 

“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”

[al-Maa’idah 5:2]

The scholars (may Allaah have mercy on them) stated that it is haraam to rent out a house to one who is going to use it in disobedience of Allaah. 

It says in Mataalib Ooli al-Nuha (3/607): It is not valid to rent out a house to be used as a church, synagogue, monastic cell, house of fire for Magian worship, for selling alcohol or gambling, because that is helping in sin and Allaah says “do not help one another in sin and transgression”. (And it is not valid) to rent the house out for music or anything else that the Lawgiver has forbidden. End quote. 

It says in al-Mawsoo’ah al-Fiqhiyyah (8/228): Because the purpose of the rental contract is to sell use of the house for a specific period, the same stipulation is made concerning its use as is made in a contract of sale, which is that there should be no shar’i impediment to the use made of it such as it being haraam, as in the case of alcohol, musical instruments and pork. According to the majority of fuqaha’ it is not permissible to rent out a house for purposes that are not acceptable according to sharee’ah, such as if the renter is going to use it as a place for drinking alcohol or gambling, or he is going to use it as a church or place of idol-worship. In that case it is haraam to take the rent just as it is haraam to give it, because that is helping in sin. End quote. 

And Allaah knows best.