Friend owes $863, not willing to pay back, wants to pay in installments...?

I have email records of his disobedience to my requets to pay him.. Hes 21, repeatedly says his mom wont let him take out a personal loan. Agrees to work 50 hours a week to pay me $200 a paycheck, to have paid me by the endof summer, agrees to pay interest.. but I need the money NOW