Can I say no if I'm not able to come in if my manager asks if I come in on a day I'm busy

I got a new job and my manager apparently called my uncle (idk why but I put him as my emergency contact) and ask if I can come in tomorrow. Which is strange because I never got a call from them asking me but called my uncle instead, and i am not able to come in because I'm trying to get things done at home (like clean my house, do laundry since I havent had much time because of school and work) and i have schoolwork to do and another job to go to at 6 pm. I was wondering if I have any right to say no

usa jobs
usa jobs resume
usa hotel jobs
usajobs
usa jobs federal government
usa job in ksa
usa jobs
usa jobs login
usa jobs gov
usajobs.gov
www.usajobs.gov
usajobs.com
usajobs
usajobs.gov official