I will offer unto thee burnt-sacrifices of fatlings. We must suppose the speaker to be either David or one of the more considerable men of the nation, for none in humbler circumstances could have offered rich sacrifices of this kind. It is probable that David was the author of the psalm, and here he signifies his intention to show a kingly liberality in his offerings. The reason why God ordered victims to be offered as an expression of thanksgiving was, as is well known, to teach the people that their praises were polluted by sin, and needed to be sanctified from without. However we might propose to ourselves to praise the name of God, we could only profane it with our impure lips, had not Christ once offered himself up a sacrifice, to sanctify both us and our services. (Hebrews 10:7) It is through him, as we learn from the apostle, that our praises are accepted. The Psalmist, by way of commendation of his burnt-offering, speaks of its incense or sweet savor; for although in themselves vile and loathsome, yet the rams and other victims, so far as they were figures of Christ, sent up a sweet savor unto God. [1] Now that the shadows of the Law have been abolished, attentionis called to the true spiritual service. What this consists in, is more clearly brought under our notice in the verse which follows, where the Psalmist tells us, that he would spread abroad the fame of the benefits which he had received from God. Such was the end designed, even in the outward ceremonies under the Law, apart from which they could only be considered as an empty show. It was this -- the fact, that they set forth the praises of the divine goodness -- which formed the very season of the sacrifices, preserving them from insipidity. In calling, as he does, upon all the fearers of the Lord, the Psalmist teaches us, that if we duly feel the goodness of God, we will be inflamed with a desire to publish it abroad, that others may have their faith and hope confirmed, by what they hear of it, as well as join with us in a united song of praise. He addresses himself to none but such as feared the Lord, for they only could appreciate what he had to say, and it would have been lost labor to communicate it to the hypocritical and ungodly.

Footnotes

1 - "Le Prophere loue yci le perfum de son holocauste, combien qu'il n'en peust monter au ciel qu' une odeur puante et infecte: mais il faut noter que les beliers et autres bestes qu'on sacrifioit flairoyent bon devant Dieu, entant que c'estoyent figures de Iesus Christ." -- Fr.

I will offer unto thee burnt sacrifices of fatlings - Margin, marrow. On the word rendered "burnt-offerings" see the notes at Isaiah 1:11. The word rendered "fatlings" is rendered in Isaiah 5:17, lambs. It may be applied to any animal considered as fat - a qualification required in sacrifices to be made on the altar, Isaiah 1:11.
With the incense of rams - The word here rendered incense is commonly applied to aromatics which were burned in the tabernacle or temple, producing a grateful odor (see the notes at Isaiah 1:13); but it seems here to be used with reference to the smoke ascending from burning rams offered in sacrifice - ascending as the smoke of incense did. The smoke thus ascending would be as grateful and acceptable as incense.
I will offer bullocks with goats - Bullocks and goats. That is, I will present sacrifices in all the forms required in worship; in all the forms that will express gratitude to God, or that will be an acknowledgment of dependence and guilt; in all that would properly express homage to the Deity. Bullocks and goats were both required in the ancient worship.

I will offer, etc. - Thou shalt have the best of the herd and of the fold; the lame and the blind shall never be given to thee for sacrifice.
The incense of rams - The fine effluvia arising from the burning of the pure fat.

I will offer unto thee burnt sacrifices of fatlings,.... Of the fattest of the flock; that is, of the best; such as Abel offered, Genesis 4:4;
with the incense of rams; or "rams with incense" (f); the Targum is,
"with sweet incense, the sacrifice of rams;''
Kimchi interprets it of incense of the fat of rams.
I will offer bullocks with goats; he proposed to offer all kind of offerings, to show gratitude and thankfulness for the favours received; by all which are meant the calves, or fruit of the lips, the sacrifices of praise, thanksgiving to God, in the name of the whole church and people of God; see Revelation 19:1.
Selah; on this word; see Gill on Psalm 3:2.
(f) "arietes cum incenso", Gejerus; so Campeusis in ibid.

I will offer--literally, "make to ascend," alluding to the smoke of burnt offering, which explains the use of "incense."
incense--elsewhere always denoting the fumes of aromatics.

I will go - One speaks in the name of all the rest. Incense - With the fat of rams, which is no less pleasing to God than incense.