“They may not be sold at the sale of a slave!” (Vayikra 25:42)
It is a negative commandment that we should not sell a Jewish slave in the way that one sells Canaanite slaves, which by announcing the sale at the selling stone. Instead, he should be sold quietly and respectfully. The source of this is the verse “They may not be sold at the sale of a slave!”, which means that they may not be sold at the public sale or at the selling stone.
The root of this commandment is well-known, as it is unfitting that a person should reduce another person’s self-respect, even if his sins have caused him to be sold, as the owner never knows if maybe the next day it will be his turn to be sold.
This commandment applies to men and to women, at a period when the Jubilee year applies, as the laws of a Jewish slave do not apply when there is no Jubilee year.
One who sells a Jewish slave in the same way as a Canaanite slave has transgressed this prohibition.