כִּ֤י תִקְנֶה֙ עֶ֣בֶד עִבְרִ֔י שֵׁ֥שׁ שָׁנִ֖ים יַעֲבֹ֑ד וּבַ֨שְּׁבִעִ֔ת יֵצֵ֥א לַֽחָפְשִׁ֖י חִנָּֽם׃
네가 히브리 종을 사면 그가 육년 동안 섬길 것이요 제칠년에는 값 없이 나가 자유할 것이요
Sefer HaMitzvot
That is that He commanded about the law of a Hebrew (Jewish) slave. And that is His, may He be blessed, saying, "When you acquire a Hebrew slave" (Exodus 21:2). And [while] most of the laws of this commandment have already been explained explicitly in the Torah, all of the laws of this commandment are explained in Tractate Kiddushin. (See Parashat Mishpatim; Mishneh Torah, Slaves 1.)