Numbers 10:10

10:10 “Also in the time when you rejoice, such as on your appointed festivals or at the beginnings of your months, you must blow with your trumpets over your burnt offerings and over the sacrifices of your peace offerings, so that they may become a memorial for you before your God: I am the Lord your God.”

Numbers 16:40

16:40 It was a memorial for the Israelites, that no outsider who is not a descendant of Aaron should approach to burn incense before the Lord, that he might not become like Korah and his company – just as the Lord had spoken by the authority of Moses.