Leviticus 10:1-11
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. Leviticus 10:1. CC 100.1
Next to Moses and Aaron, Nadab and Abihu had stood highest in Israel. They had been especially honored by the Lord, having been permitted with the seventy elders to behold His glory in the mount. But their transgression was not therefore to be excused or lightly regarded. All this rendered their sin more grievous. Because men have received great light, because they have, like the princes of Israel, ascended to the mount, and been privileged to have communion with God, and to dwell in the light of His glory, let them not flatter themselves that they can afterward sin with impunity, that because they have been thus honored, God will not be strict to punish their iniquity. This is a fatal deception. The great light and privileges bestowed require returns of virtue and holiness corresponding to the light given. Anything short of this, God cannot accept. Great blessings or privileges should never lull to security or carelessness. They should never give license to sin or cause the recipients to feel that God will not be exact with them.... CC 100.2
Nadab and Abihu had not in their youth been trained to habits of self-control.... Habits of self-indulgence, long cherished, obtained a hold upon them which even the responsibility of the most sacred office had not power to break. They had not been taught to respect the authority of their father, and they did not realize the necessity of exact obedience to the requirements of God. Aaron's mistaken indulgence of his sons prepared them to become the subjects of the divine judgments. CC 100.3
God designed to teach the people that they must approach Him with reverence and awe, and in His own appointed manner. He cannot accept partial obedience. It was not enough that in this solemn season of worship nearly everything was done as He had directed.... Let no one deceive himself with the belief that a part of God's commandments are nonessential, or that He will accept a substitute for that which He has required.4Patriarchs and Prophets, 359, 360. CC 100.4