Exodus 30:1

1.And thou shalt make an altar. God now issues His commands respecting the altar of burnt incense, whereby the people were assured that the odor of the worship under the Law was sweet to Him. This ceremony indeed also prevailed among the Gentiles; whence there is frequent mention made by heathen authors of incense-burning; but what its object was they knew not themselves, nor did they care to reflect upon its proper intention, since they conceived themselves to have done all that was required of them, by the bare sign itself. In this way, however, God would encourage His believing people, by giving them to know that the worship which they offered at this command sent up to him a sweet savor. Meanwhile He admonished them diligently to beware lest any uncleanness should profane their sacrifices, but that they should come cleansed and pure into His sight. And David applies this type specially to prayer, when he says:

"Let my prayer be set forth before thee as incense.”
(Psalms 131:2.)

Therefore, as the other altar of which we have been hearing, was devoted to the victims for the purpose of propitiating God, so also this altar perfumed the sacrifices with the odor of its incense, that they might be acceptable to God. Hence it was placed near the ark of the testimony, though with the vail between, that its savor might ascend directly to God without any let or hindrance. There is no ambiguity in the words, except that some think there is a repetition where it is said, “every morning,” and “between the two evens;” (152) others suppose that there are two separate oblations, and this latter view is the more probable, i.e., that the incense was offered morning and evening. He afterwards forbids either the altar itself to be transferred to other uses, or any other kind of incense to be burnt upon it; of this he will speak elsewhere.