Offer unto God thanksgiving - The word rendered “offer” in this place - זבח zâbach - means properly “sacrifice.” So it is rendered by the Septuagint, θῦσον thuson - and by the Vulgate, “immola.” The word is used, doubtless, with design - to show what was the “kind” of sacrifice with which God would be pleased, and which he would approve. It was not the mere “sacrifice” of animals, as they commonly understood the term; it was not the mere presentation of the bodies and the blood of slain beasts; it was an offering which proceeded from the heart, and which was expressive of gratitude and praise. This is not to be understood as implying that God did not require or approve of the offering of bloody sacrifices, but as implying that a higher sacrifice was necessary; that these would be vain and worthless unless they were accompanied with the offerings of the heart; and that his worship, even amidst outward forms, was to be a spiritual worship.
And pay thy vows unto the Most High - To the true God, the most exalted Being in the universe. The word “vows” here - נדר neder - means properly a vow or promise; and then, a thing vowed; a votive offering, a sacrifice. The idea seems to be, that the true notion to be attached to the sacrifices which were prescribed and required was, that they were to be regarded as expressions of internal feelings and purposes; of penitence; of a deep sense of sin; of gratitude and love; and that the design of such sacrifices was not fulfilled unless the “vows” or pious purposes implied in the very nature of sacrifices and offerings were carried out in the life and conduct. They were not, therefore, to come merely with these offerings, and then feel that all the purpose of worship was accomplished. They were to carry out the true design of them by lives corresponding with the idea intended by such sacrifices - lives full of penitence, gratitude, love, obedience, submission, devotion. This only could be acceptable worship. Compare the notes at Isaiah 1:11-17. See also Psalms 76:11; Ecclesiastes 5:5.