Rashi on Leviticus 8:28/רש"י על ויקרא ח׳:כ״ח

1ויקטר המזבחה [AND MOSES TOOK THEM FROM OFF THEIR HANDS] AND CAUSED THEM TO ASCEND IN FUMES AT THE ALTAR — Moses (though a non-priest) was officiating during the seven days of installation [in a white garment] (Avodah Zarah 34a).

2על העלה [AND MOSES … CAUSED THEM TO ASCEND IN FUMES] על העלה — after the burnt offering (על is taken in the sense of besides, in addition to the burnt offering. Hence he burnt it after the burnt offering). We do not find in any passage, that the shoulder of peace-offerings was burnt except in the case of this alone (cf. Rashi on Exodus 29:22).