I would refer someone I'm friends with if I know them well, understand what they would be like to work with, and understand the job/company well enough. After

I would refer someone I'm friends with if I know them well, understand what they would be like to work with, and understand the job/company well enough. After all, I've lived with some people that I never worked with. Surely I know them well enough to recommend them for jobs, even though I have not ever worked alongside them.