Owner actually expects free work

I'm a massage therapist and the owner of the salon I work at texted me this when I asked for my unbooked time blocked off for the day. If I have no appointments I block off four hours into the future so I'm not on call. I am only paid commission for my massages and no wage for anything else I do. Ive had a lot of jobs I've been abused at but I've never had someone be so bold as to tell me to work for free and promote their business on my social media pages in order to not be on call for free.