What is "ba'Eis ha'Hi" referring to? Why does it insert the choosing of the Tribe of Levi here?
Rashi and Rashbam: It is referring to the episode of the Golden Calf 1 - and is mentioned here, following the episode of B'nei Ya'akon because, just as the tribe of Levi did not go astray by the Eigel, so too did they not go astray there, and that is why Hashem chose them, as the Pasuk goes on to explain.
Ramban: It refers to the same time as "ba'Eis ha'Hi" in Pasuk 1 - after Hashem instructed Moshe to carve out a second set of Luchos, when He made up with K'lal Yisrael and commanded them to build the Mishkan, that is when the Levi'im were chosen. 2
Seforno: Moshe was pointing out that, since, following the sin of the Eigel ha'Zahav, Hashem chose the Tribe of Levi to serve Him and the rest of Yisrael remained unworthy of doing so, it is a sign that he only achieved with his Tefilah that Hashem did not destroy them, but not a complete pardon.
Why does the Torah ascribe the choosing of the Tribe of Levi to the episode of the Golden Calf, when, in fact, they were chosen only after the first counting in Iyar of the second year (See Bamidbar 1:1)?
Ramban #2: Refer to 10:8:1:2.
What has "La'amod Lifnei Hashem Leshorso u'Levarech bi'Shemo" to do with the Levi'im?
Rashi: This Pasuk is talking about the entire Tribe of Levi, including the Kohanim. 1
Rashi in Zevachim, 26a also learns from this Pasuk that the Shechitah of Kodshim Kalim and the Kabalas ha'Dam must be performed in the Azarah.
What are the connotations of "Levarech bi'Shemo"?
Rashi (Eruvin, 18b): It means bless the people with the Name of Hashem - the way it is written. 1
Which is what the Kohanim did in the Beis ha'Mikdash.
Why does the Torah add the words "Ad ha'Yom ha'Zeh"?