Some slave owners or overseers were sadists, and derived sexual pleasure from abusing their slaves. See RE Lee, known as a cruel slave master before the civil war. He seemed to have a particular interest, to say the least, in young female slaves. Jeff Davis also fathered at least one of his slaves.
Horses up to 2500 lbs are routinely controlled with small whips, despite their value. Whipping a horse or a slave was not considered abuse. Raping a slave was not considered abuse. Selling a slave woman’s child was not considered abuse.
The only way to reply to a liar and a particularly stupid one is to say: “You are a Liar”.