What is the meaning of "ba'Ser"?
Rashi: In the tithe.
Ibn Ezra: It should say b'Ha'aser. [The Hei is omitted,] like "Latzbos Beten", "Lanchosam ha'Derech."
Why is the Kohen with the Levi in Ma'aser?
Malbim: Ezra fined the Leviyim, that also Kohanim will take Ma'aser (Yevamos 86b). Terumas Ma'aser must be given to a Kohen, and even from what a Levi grew.
R. Elazar ben Azaryah holds that after Ezra fined the Leviyim, we give Ma'aser Rishon only to a Kohen (Chulin 131b). Leviyim did not receive at all. How does he explain our verse?
Tosfos (Yevamos 86b DH Mipnei): He learns from "Havi'u... ha'Ma'aser El Beis ha'Otzar" (Mal'achi 3:10), i.e. Lishkas ha'Kohanim. The decree had not spread so much in the days of Ezra, so Leviyim still collected with Kohanim.
Ya'avetz (Yevamos 86b): When Binyan ha'Mikdash ceased, most Leviyim returned to Bavel with Zerubavel. Ezra forced them to return, and fined that they not receive at all. There was no fine against the Leviyim who remained in Eretz Yisrael.
What is "Ma'asar ha'Ma'aser"?
Rashi: The Leviyim take a 10th of the Ma'aser, and bring it to the Kohanim, for they did not leave Beis ha'Mikdash.
