Leviticus 9:20
And they put the fat upon the breasts, and he burnt the fat upon the altar:
Cross-reference
Leviticus 3:14–17
Parallel
Leviticus 3:14-17 commands burning the fat of peace offerings on the altar, which Aaron does here by burning the fat placed on the breasts.
Leviticus 7:29–34
Parallel
Leviticus 7:29-34 explains the breast as a wave offering for priests; here fat is placed on the breasts before burning.