Rashi on Leviticus 8:36/רש"י על ויקרא ח׳:ל״ו

1ויעש אהרן ובניו SO AARON AND HIS SONS DID [ALL THE THINGS] — This is stated to tell their praise — that they did not turn to the right nor to the left (cf. Sifra, Tzav, Mechilta d'Miluim 1 38).