Why does the Torah see fit to inform us that Aharon and his sons did everything that Hashem commanded Moshe?
Rashi: To teach us their praise in that they did not deviate one iota from what Moshe had instructed them. 1
See Sifsei Chachamim, who lists the many places where the Torah writes this phrase and explains why it does not do so in connection with the Korban Pesach (See Bamibar 9:5).
Why does the Torah deviate from the usual expression "Ka'asher Tzivah Hashem es Moshe"?