You shall surely furnish him liberally from your flock and from your threshing floor and from your winepress; of that with which Hashem your God has blessed you, you shall give to him.
English: "You shall surely furnish" — It was taught: From where do we know that if you have furnished him once you must furnish him even a hundred times? From the doubled language "furnish, you shall furnish"—even a hundred times.
On the daf / in context: Each successive release of the same person (or of successive slaves) renews the obligation of the grant.
Type of Learning
Derash on the verse (Kiddushin) — repeated grants are required.
What Is Learned
The obligation to furnish a departing slave applies even a hundred times; each release renews the duty.