English: "For he has no portion" — to declare what caused this.
On the daf / in context: The verse itself supplies the reason for the obligation: the Levi’s lack of inheritance is the ground of the duty to support him.
Type of Learning
Derash on the verse (Sifrei) — the reason for the obligation is stated explicitly.
What Is Learned
The Torah itself explains that the duty not to forsake the Levi arises from his having no portion or inheritance with the rest of Israel.