John Calvin Commentary Hebrews 13:15

"Through him then let us offer up a sacrifice of praise to God continually, that is, the fruit of lips which make confession to his name." — Hebrews 13:15 (ASV)

By him, therefore, let us offer the sacrifice of praise to God, etc. He returns to that particular doctrine he had referred to, concerning the abrogation of the ancient ceremonies, and he anticipates an objection that might have been raised. For as the sacrifices were attached as appendages to the tabernacle, when this was abolished, it follows that the sacrifices also must have ceased. But the Apostle had taught us that as Christ suffered outside the gate, we are also called there, and that for this reason the tabernacle must be forsaken by those who would follow Him.

Here a question arises: did any sacrifices remain for Christians? For this would have been inconsistent, as they had been instituted for the purpose of celebrating God's worship. The Apostle, therefore, in due time meets this objection and says that another kind of sacrifice remains for us, which pleases God no less, even the offering of the calves of our lips, as the Prophet Hosea says (Hosea 14:2).

Now, that the sacrifice of praise is not only equally pleasing to God, but of greater importance than all those external sacrifices under the Law, appears evident from Psalm 50. For God there repudiates all these as things of no value and commands that the sacrifice of praise be offered to Him.

We therefore see that it is the highest worship of God, justly preferred to all other exercises, when we acknowledge God's goodness by thanksgiving. Indeed, this is the ceremony of sacrificing which God commends to us now.

Yet there is no doubt that under this one part, the whole of prayer is included. For we cannot give Him thanks unless we are heard by Him, and no one obtains anything except one who prays. In short, He means that without brute animals, we have what is required to be offered to God, and that He is thus rightly and truly worshipped by us.

But as it was the Apostle’s design to teach us the legitimate way of worshipping God under the New Testament, so, in passing, he reminds us that God cannot be truly invoked by us and His name glorified, except through Christ the Mediator. For it is He alone who sanctifies our lips (which otherwise are unclean) to sing the praises of God; and it is He who opens a way for our prayers, who, in short, performs the office of a priest, presenting Himself before God in our name.