Hebrews owned slaves? Yeah! However, even the lowliest scullery maid got a day off, every week. That was the Law.

Egyptian and caananite rulers could, and probably did, work their slaves seven days a week - and beat them to death, for what? ... a few sheets n giggles?   Meanwhile, the Hebrews - from their princes, to the poor schlep who shoveled horse manure - stopped work at 6pm friday evening, because that was the start of their Sabbath.  Whatever farm tool joe slave was using, by 6pm, that rake or hoe was wiped off and hanging on its hook.

By 6pm saturday, the Sabbath was over.  But ya know what?  In that region of the world, it's about getting on dark by 8pm.  So, saturday at 6pm, what's joe slave going to do?  Maybe he'll head out to the shed and sharpen the sickle, or check the wagon wheel - he recalled it sounding rather funny late thursday.  Meanwhile, during that two-time hour work-window, sally the scullery slave would perhaps, sharpen some kitchen knives (metal was expensive - so things had to be taken care of) or maybe she'd snap some green beans.  Or maybe she'd give the window wells a wipe/give the walkway a sweep. 

Unlike the egyptian and caananite slave owners, in Hebrew sociey, if your slave accidently knocked over your favorite vase, and you beat the living tar out of that slave, you could end up in big trouble for that.  Yep!  Again and again, Hebrews were reminded that their ancestors suffered under BRUTAL working conditions.  

For the most part, however, "slaves" in Hebrew society, were Hebrews themselves, who'd ran into financial trouble.  So, dennis the debtee would work seven years to pay what he owed; at the end of the term, he'd be given sufficient resources to start over as a free man.

But the most important thing was:  a slave, like anybody else in Hebrew society, was taught about the Lord God's ways - what He expects from His people, be they princes or poop shovellers.  Meanwhile Pagan rulers didn't give one iota about the eternal souls of their laborers.