Negative commandment · Lo Ta’aseh #259 of 613
Not to make a Hebrew servant perform rigorous work
שלא לעבוד בעבד עברי בפרך
The verse · Vayikra 25:43
לֹא־תִרְדֶּה בוֹ בְּפָרֶךְ וְיָרֵאתָ מֵאֱלֹהֶיךָ
“Thou shalt not rule over him with rigour; but shalt fear thy God.”
The Rambam’s words
Not to make a Hebrew servant perform rigorous work, as [Leviticus 25:43] states: "Do not rule over him with rigor."
שלא לעבוד בעבד עברי בפרך, שנאמר "לֹא תִרְדֶּה בּוֹ בְּפָרֶךְ" (ויקרא כה, מג).
Who & when
“And this commandment is practiced by males and females at the time the Jubilee is practiced.”
Where in the Mishneh Torah
Hilchot Slaves הלכות עבדים