Tertullian

Now this is the spiritual victim which has set aside the earlier sacrifice.… The gospel teaches what God demands. "The hour is coming," he says, "when the true worshipers will worship the Father in spirit and in truth." … We are the true worshipers and true priests who, offering our prayer in the spirit, offer sacrifice in the spirit—that is, prayer—as a victim that is appropriate and acceptable to God; this is what he has demanded and what he has foreordained for himself.