Exodus 30:7-8

30:7 Aaron is to burn sweet incense on it morning by morning; when he attends to the lamps he is to burn incense. 30:8 When Aaron sets up the lamps around sundown he is to burn incense on it; it is to be a regular incense offering before the Lord throughout your generations.

Hebrews 5:4

5:4 And no one assumes this honor on his own initiative, but only when called to it by God, as in fact Aaron was.