Deuteronomy 15:14 "You shall give him gifts"

Positive Mitzvah 232 tells us how a Jew can be sold as a slave.

He is sold for a limited period of time and the master pays the money at the time of sale. Therefore, when we release such a slave, one might think there is no need to pay him for his work. After all, the master paid for his service beforehand.

The Torah, however, demands that we be considerate and care for others. When it is time to free a Jewish slave, he must be presented with gifts which will help him begin to live on his own.