What is this Pasuk coming to teach us?
Rambam (Sefer ha'Mitzvos Lo Sa'aseh 233): It places a Lo Sa'aseh on a master who sends away his Eved Ivri without giving him gifts. 1
Hadar Zekenim, Rosh: The verse discusses one whom Beis Din sold, so he has nothing, therefore one must give him gifts. (Some say that also one who sold himself gets gifts (Kidushin 14b). Presumably, also one who sold himself, did so because he had no money! - PF)