What did Moshe mean when he said to the Levi'im "Mil'u Yedchem ... "?
Seforno: He meant that they should acquire perfection for their hands today to be ready to serve Hashem in His Mikdash. 3
Rashbam: He meant that each one of them has consecrated his hands with a Korban on behalf of Hashem. 4
Targum Onkelos and Targum Yonasan: He meant that they should bing Korbanos today to atone for the blood that they spilt!. 5
Refer to 28:41:2:1*.
To take over from the Bechoros, who had been the priests until now.
Rashbam: By stretching out their hands to kill their own sons and brothers for the sake of Hashem. See also Bamidbar 32:12.
What reward did the Levi'im receive for this act?
Da'as Zekenim and Hadar Zekenim (in Pasuk 26): Moshe blessed them 1 in Parshas ve'Zos ha'Brachah, even though Ya'akov had not blessed Levi. 2
Mishnas R. Aharon (4 p.21): They merited "Yoru Mishpatecha le'Yisrael" because at a time of slackening, they did not bow to the Eigel; but the contrary, they answered Moshe's call "Mi la'Hashem Elai!"
Da'as Zekenim and Hadar Zekenim: Likewise, Moshe blessed Reuven (even though Ya'akov did not), because they fulfilled the Mitzvah to cross the Yarden and fight - He had Ru'ach ha'Kodesh to know that they would do so. Shimon, on the other hand was not blessed by either Ya'akov or Moshe (PF)
