The Talmud Yerushalmi (Rosh Hashanah 3:5) teaches that the Jewish people were taught this law while still enslaved in Egypt based on the verses in Jeremiah 34:13-14. A question can be asked as follows: Why was the law pertaining to the "Jewish bondsman" taught to the Jewish people specifically while they were still enslaved? It seems strange that a poor enslaved Israelite should be taught the laws pertaining to a Jewish master? I would like to propose the following original answer, Bezrat Hashem.

Besides the laws pertaining to the "Jewish bondsmen", G-d wanted to teach the Israelites a fundamental concept,namely that G-d Almighty has the power and ability to make a slave a master, and a master into a slave. Just imagine an Israelite slave studying the laws pertaining to the master, its surely the best time to instill in their minds that shortly they will be freed and be masters themselves.A slave does not himself have slaves, yet a free man can surely have slaves. Nothing is beyond G-d's power. This was surely the most opportune time to instll this concept into their minds. What better time than when they themselves are enslaved, and studying the laws of being a Jewish master.

Its a contradiction, yet a most potent manner to educate the Israelites that G-d can tranform a slave into a master in an instant.This provided the Israelites with much hope.The Israelites needed to know that G-d is surely in control. They needed to be taught the concept of "Emunah", namely that G-d exists and that G-d is surely in control.Only G-d has the power and ability to free slaves, not their masters.Have a good Shabbos