The very first of the laws which were taught (in addition to the laws of Pesach and of matters that memorialize the Redemption from Egypt) to Israel are the laws of the Hebrew servant.
Two reasons can be understood for the choice of this law as the first of the Mishpatim.
1) Compassion on the lowly or the oppressed is a fundamental Torah-attitude, and it is constantly pointed out in the Sacred Scriptures as one of the chief attributes of Hashem. Because of this aspect, the laws of the Hebrew slave deserve the first mention
2) The laws of the Hebrew slave are a memorial of the Going Out of Egypt. The Egyptians called our fathers “Hebrew” (not Israelites) (1:16, 2:6, and elsewhere), and the Torah treatment of the “Hebrew slave” is a parallel demonstration of Hashem’s compassion upon His people in Egypt. “On the seventh year you shall send him away free from you. And when you send him away free from you, you should not send him away empty-handed. You shall furnish him from your flock and from your grain-pile and from your wine-press” (Dvarim 15: 12-14).
This is a memorial of the deliverance from the bondage of Egypt: “And when you shall depart, you shall not depart empty-handed” (3:2 1), as Hashem had foretold to Abraham: “And afterward they shall go out with great wealth” (Breshis 15:14).
And the Torah adds: “And you shall remember that you were a slave in the land of Egypt... therefore I command you this matter today.” (Dvarim 15:15)
Thus even the Mishpatim serve as a reminder of the Going Out of Egypt.
Just as Israel did not leave Egypt empty-handed, so also does the Hebrew slave not leave empty-handed from his six years of servitude.
3) The Eved Ivri should correctly be called Eved Yisraeli, for in the language of the Jews the word Ivri is never used except when speaking to gentiles.
But the Israelite bondsman is called by the name that the Egyptians called our fathers in Egypt. Thus the Eved Ivri is used by the Torah to commemorate the bondage of Israel in Egypt.(A Nation is Born)