‘And Yahweh spoke to Aaron, saying,'
This is the first time that God has spoken directly to Aaron, demonstrating his new status. From now on until Leviticus 15, God will speak sometimes ‘to Moses and to Aaron' (Leviticus 11:1; Leviticus 13:1; Leviticus 15:1) and sometimes just ‘to Moses' (Leviticus 12:1; Leviticus 14:1). The alternation suggests that the aim is to bring in Aaron while retaining the priority of Moses. But speaking solely to Aaron here, the only example, demonstrates the importance of the subject for Aaron. It is he and his remaining sons who are directly responsible for maintaining the holiness of the Sanctuary.