“And Nadab and Abihu, the sons of Aaron, took either of them his censer, and put fire therein, and put incense thereon, and offered strange fire before the LORD, which He commanded them not. And there went out fire from the LORD, and devoured them, and they died before the LORD. Then Moses said unto Aaron, ‘This is it that the LORD spake, saying, I will be sanctified in them that come nigh Me, and before all the people I will be glorified.’ And Aaron held his peace.” Leviticus 10:1-3 (KJB)
The following is from F. B. Meyer Commentary of chapter 9 verse 22 through 10 verse 11…
A DEED THAT TURNED JOY INTO GRIEF
There was a double blessing. First, Aaron blessed the people when he stood against the altar, Lev_9:22, and afterward, when he came out of the Tabernacle, Lev_9:23. We find here the analogue of the double blessing which our Lord gives His own. When He came from offering His supreme sacrifice on Calvary, which was burned-offering, peace-offering, sin- and trespass-offerings combined, He blessed His own. We are told that as He blessed them He was borne upward to heaven, Luk_24:51; but we expect another blessing from Him, when He shall come forth out of the heavenly Temple and extend His hands in benediction, using perhaps the very words of the ancient benediction. But take care lest you ever introduce strange fire into your worship-i.e., the fire of your own emotions, enthusiasm and excitement. Ponder those mighty words in Lev_10:3. We must not rush carelessly into the divine presence, though by the blood of Jesus we have been made nigh, Eph_2:13.