Leviticus 3:5

Lev 3:5 And Aaron’s sons shall burn it on the altar upon the burnt sacrifice, which [is] upon the wood that [is] on the fire: [it is] an offering made by fire, of a sweet savour unto the LORD.

Ver. 5. Upon the burnt sacrifice. ] Which was first offered, to teach us that sin must be pardoned ere our thank offerings can be accepted. It is, therefore, ordinarily, best to begin our prayers with confession of sin, and petitions for pardon through Christ.