Leviticus 10:1

And Nadab and Abihu - took either of them his censer - The manner of burning incense in the temple service was, according to the Jews, as follows: -

"One went and gathered the ashes from off the altar into a golden vessel, a second brought a vessel full of incense, and a third brought a censer with fire, and put coals on the altar, and he whose office it was to burn the incense strewed it on the fire at the command of the governor. At the same time all the people went out of the temple from between the porch and the altar. Each day they burned the weight of a hundred denaries of incense, fifty in the morning, and fifty in the evening. The hundred denaries weighed fifty shekels of the sanctuary, each shekel weighing three hundred and twenty barleycorns; and when the priest had burned the incense, he bowed himself down and went his way out. See Maimonides' Treatise of the Daily Service, chap. iii. So when Zacharias, as his lot fell, burned incense in the temple, the whole multitude of the people were without at prayer while the incense was burning, Luke 1:9 , Luke 1:10 . By this service God taught them that the prayers of his faithful people are pleasing to him, whilst our High Priest, Christ Jesus, by his mediation puts incense to their prayers; (see Psalm 141:2 ; Romans 8:34 ; Hebrews 8:1 , Hebrews 8:2 ; Hebrews 9:24 ; Revelation 8:3 , Revelation 8:4 ;); for the priests under the law served unto the example and shadow of heavenly things; Hebrews 8:5 ." See Ainsworth in loco.

In the preceding chapter we have seen how God intended that every part of his service should be conducted; and that every sacrifice might be acceptable to him, he sent his own fire as the emblem of his presence, and the means of consuming the sacrifice - Here we find Aaron's sons neglecting the Divine ordinance, and offering incense with strange, that is, common fire, - fire not of a celestial origin; and therefore the fire of God consumed them. So that very fire which, if properly applied, would have sanctified and consumed their gift, became now the very instrument of their destruction! How true is the saying, The Lord is a consuming fire! He will either hallow or destroy us: he will purify our souls by the influence of his Spirit, or consume them with the breath of his mouth! The tree which is properly planted in a good soil is nourished by the genial influences of the sun: pluck it up from its roots, and the sun which was the cause of its vegetative life and perfection now dries up its juices, decomposes its parts, and causes it to moulder into dust. Thus must it be done to those who grieve and do despite to the Spirit of God. Reader, hast thou this heavenly fire? Hear then the voice of God, Quench not the Spirit. Some critics are of opinion that the fire used by the sons of Aaron was the sacred fire, and that it is only called strange from the manner of placing the incense on it. I cannot see the force of this opinion.

Which he commanded them not - Every part of the religion of God is Divine. He alone knew what he designed by its rites and ceremonies, for that which they prefigured - the whole economy of redemption by Christ - was conceived in his own mind, and was out of the reach of human wisdom and conjecture. He therefore who altered any part of this representative system, who omitted or added any thing, assumed a prerogative which belonged to God alone, and was certainly guilty of a very high offense against the wisdom, justice, and righteousness of his Maker. This appears to have been the sin of Nadab and Abihu, and this at once shows the reason why they were so severely punished. The most awful judgments are threatened against those who either add to, or take away from, the declarations of God. See Deuteronomy 4:2 ; Proverbs 30:6 ; and Revelation 22:18 , Revelation 22:19 .