The Context

When a Jewish slave’s term comes to an end, the owner is commanded to give him a severance gift.

“And when you send him forth free from you, you shall not send him forth empty-handed...” The verse then supplies the reason, “And you shall remember that you were a slave in the land of Egypt, and the Lord, your God, redeemed you; therefore, I am commanding you this thing today.” (Devarim 15:13-15)

The sages in the Sifri infer the rationale: Just as when the Jews left Egypt, G-d gave them the spoils of Egypt from the Egyptian homes, and then gifted them again with the spoils that washed up on the shores of the sea, so, too, an owner must give an abundance of gifts to his former slave.