Two sons of Moses’s brother Aaron made an offering of incense to the Lord. But they did it wrong, so God killed them with fire. Moses explained that this was how God proved that he was holy and honorable. Aaron said nothing.
Moses told Aaron and his remaining sons not to mourn for the dead sons, because if they did, God would get angry and kill them. And maybe all the other Israelites, too. Moses also told them to eat a grain offering in the sanctuary area.
Then, when Moses found out that they hadn’t eaten a sin offering in the sanctuary area, he was angry. But Aaron said God might not have been pleased if they had eaten the sin offering, since he wasn’t pleased about that other offering. Moses decided Aaron was right.
The moral of the story
It’s best not to make any offerings to God, just to be safe.