John Calvin Commentary Exodus 30:1

"And thou shalt make an altar to burn incense upon: of acacia wood shalt thou make it." — Exodus 30:1 (ASV)

And you shall make an altar. God now issues His commands concerning the altar of burnt incense, by which the people were assured that the fragrance of the worship under the Law was sweet to Him. Indeed, this ceremony also prevailed among the Gentiles, which is why there is frequent mention by pagan authors of incense-burning; but they did not know its object themselves, nor did they care to reflect upon its proper intention, since they believed they had done all that was required of them by the mere sign itself.

In this way, however, God would encourage His believing people by letting them know that the worship which they offered at His command sent up to Him a sweet fragrance. Meanwhile, He diligently admonished them to beware that no uncleanness should profane their sacrifices, but that they should come cleansed and pure into His sight. And David especially applies this type to prayer, when he says:

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

Therefore, as the other altar, which we have been discussing, was devoted to the animal sacrifices for the purpose of propitiating God, so also this altar perfumed the sacrifices with the fragrance of its incense, so that they might be acceptable to God. Therefore, it was placed near the ark of the testimony, though with the veil between, so that its fragrance might ascend directly to God without any obstruction 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 offerings, and this latter view is the more probable, that is, that the incense was offered morning and evening. He afterwards forbids either the altar itself to be used for other purposes or any other kind of incense to be burned upon it; he will speak of this elsewhere.

¹⁵² A. V., Margin, Margin, ver. 8..