תצוה: מזבח הקטורת

You shall make an altar for burning incense; make it of acacia wood. It shall be a cubit long and a cubit wide—it shall be square—and two cubits high, its horns of one piece with it. Overlay it with pure gold: its top, its sides round about, and its horns; and make a gold molding for it round about. And make two gold rings for it under its molding; make them on its two side walls, on opposite sides. They shall serve as holders for poles with which to carry it. Make the poles of acacia wood, and overlay them with gold. Place it in front of the curtain that is over the Ark of the Pact—in front of the cover that is over the Pact—where I will meet with you. On it Aaron shall burn aromatic incense: he shall burn it every morning when he tends the lamps, and Aaron shall burn it at twilight when he lights the lamps—a regular incense offering before the LORD throughout the ages. You shall not offer alien incense on it, or a burnt offering or a meal offering; neither shall you pour a libation on it. Once a year Aaron shall perform purification upon its horns with blood of the sin offering of purification; purification shall be performed upon it once a year throughout the ages. It is most holy to the LORD.

AND THOU SHALT MAKE AN ALTAR TO BURN INCENSE UPON. Now the altar of incense being one of the articles in the inner part of the Sanctuary, it should have been mentioned with the table and the candelabrum together with which it was placed, as indeed they are mentioned at the actual construction in the section of Vayakheil. But the reason for mentioning it here after the Tabernacle and all its vessels and the sacrifices [for the seven days of consecration], is because of what He said at the completion of them all, and the Tent shall be sanctified by My Glory; and I will dwell among the children of Israel. Therefore He now said that they will yet be obliged to make an altar for the burning of incense — to burn it for the glory of G-d. This was a secret which was transmitted to Moses our Teacher, that the incense checks the plague. For the incense is of the attribute of justice, as it is said, they shall put incense ‘b’apecha’, which is of the root v’charah api (My wrath shall wax hot). It is for this reason that He said of strange incense, and before all the people I will be glorified, meaning that they will know My glory, for He will not pardon your transgression. For this reason too He said here [of the altar of incense], And thou shalt put it before the veil that is by the ark of the Testimony, before the ark-cover that is over the Testimony, where I will meet with thee. For why is it necessary to speak at length of all these matters, and why did He not say briefly, “and thou shalt put it before the ark of the Testimony in the Tent of Meeting,” as He said in the section of Vayakheil? But the extended form of the verse here indicates the purport [of the altar of incense].

And thou shalt make an altar to burn incense (Exod. 30:1). What do the letters in the word ketoret (“incense”) stand for? The kuf stands for kedushah (“sanctification”), tet for taharah (“purity”), resh for rahamim (“mercy”), and ta for tikvah (“hope”). A cubit shall be the length thereof, and a cubit the breadth thereof; and two cubits shall be the height thereof (ibid.). What was the purpose of this altar? After they committed the act of erecting the golden calf, the Holy One, blessed be He, complied with his (Moses’) request, as is said: And the Lord repented of the evil (ibid., v. 14). Whereupon Moses said: Master of the Universe, You have already agreed with me (to forgive them), but who will make known to those who come unto the world that You are reconciled with Israel? He replied: Let them make Me a Sanctuary, that I may dwell among them (Exod. 25:8), and let them offer sacrifices within it, and I will accept their lamb.

Since many beasts were daily slaughtered in the holy place, the flesh cut in pieces and the entrails and the legs burnt and washed, the smell of the place would undoubtedly have been like the smell of slaughter-houses, if nothing had been done to counteract it. They were therefore commanded to burn incense there twice every day, in the morning and in the evening (Exod. 30:7, 8), in order to give the place and the garments of those who officiated there a pleasant odour. There is a well-known saying of our Sages, "In Jericho they could smell the incense" [burnt in the Temple]. This provision likewise tended to support the dignity of the Temple. If there had not been a good smell, let alone if there had been a stench, it would have produced in the minds of the people the reverse of respect; for our heart generally feels elevated in the presence of good odour, and is attracted by it, but it abhors and avoids bad smell.

“And you shall make an altar to burn the incense; make it of acacia wood.” (Shemot, 30:1)
This week’s Parsha mentions all of the vessels except for the golden incense altar. We can understand this through the Zohar (Bamidbar, 151b), which asks, “what is incense? It is the connection of all.” This hints that everything, even what is done in “his world, is all connected in God’s will, and without His will nothing at all would be done. One who misunderstands this could come to irreverence, God forbid, since everything that happens is permitted from Heaven. Therefore the incense altar, which represents this understanding, was not said in Parshat Truma, but only after the explanations of the priestly garments in this Parsha, which teach of the great fear of God and vigilant guarding from the vain pleasures of this world. As it is written in the Gemara (Arachin, 16a), “the ctonet, or tunic of chequer work, makes atonement for the spilling of blood,” and so it is with all of the garments. By means of his priestly garments, the Cohen sends great fear of God to the heart of each one in Israel. Then after the Cohen has instilled such fear in the heart of Israel, then they have the ability to receive the simcha and love that comes from the power of the incense.

Exodus 30,1. “you are to construct an altar for the ‎burning of incense.” Nachmanides questions why mention ‎of this altar has been left until this point, whereas all the other ‎furnishings of the Tabernacle have been described in Parshat ‎T’rumah., where we would have expected to find this ‎paragraph also.‎
I believe that at this point, after G’d (through Moses) had ‎appointed Aaron and sons as priests, there might be a challenge ‎to this appointment, as indeed we find later in Parshat ‎Korach. If, the command to build the golden altar for the ‎burning of incense was commanded only after Aaron’s ‎appointment, G’d hoped that it would become clear to the people ‎that the appointment had not been at the instigation of Moses ‎but was the result of instructions Moses had received from G’d.‎