@Goldenseal No, it's not just "can't order the slaves to kill themselves", that's why I explicitly mentioned Roman-era slavery; Slaves were meant to obey orders, certainly, but any order they took exception to they could and often did ignore; there were even laws proscribing exactly how you were allowed to punish slaves that did so, and how slaves were to be treated in general, as well. Seriously, there's a lot of rule and regulation behind Roman-era slavery; Here's a small taste of what is written. https://facultystaff.richmond.edu/~wstevens/history331texts/slavery.html
Of course, there are bound to have been plenty of Romans who still mistreated their slaves, as evidence in Pompeii shows that one set of farm slaves were left shackled even unto their death, and the remains showed malnutrition and neglect, so it's not like it was smelling of roses all the time, either.