There is no such language as Muslim. "Muslim" is a religion.
Muslim people speak many different languages. The majority of Muslims in the world Muslims speak Indonesian, whereas Arabic is the traditional language of the religion.
In Arabic it is: ''Keefak?'' if you were talking to a male , but you say ''Keefek?'' if you were talking to a female. You can also say ''Keef el haal?'' which works for both. If you were talking to a bunch of people, you say ''Keefkom?''