Why did Hashem instruct Moshe to cook the Eil ha'Mi'lu'im in the Azarah?
Rashi and Ramban: Because, although a Shelamim is generally Kodshim Kalim (which may be eaten anywhere in Yerushalayim for two days and one night), the Eil ha'Mulu'im was Kodshei Kodshim, which could only be eaten in the Azarah. 1 (and for one day and a night). 2
See Ramban, who is in a quandary as to whether it was a Hora'as Sha'ah that the B'sar Milu'im had to be cooked by a Kohen (Moshe), or whether, as the Ibn Ezra explains, Hashem was simply instructing Moshe to see that it was cooked, either by himself or by somebody else - - like we find above in 17:5 and in Melachim 1, 6:14 (Ramban).
Like the Zivchei Shalmei Tzibur on Shavu'os (Ramban).