And a fire came out from the LORD and consumed the two hundred and fifty men who were offering incense. Numbers 16:35 (NKJV)
So Eleazar the priest took the bronze censers, which those who were burned up had presented, and they were hammered out as a covering on the altar, to be a memorial to the children of Israel that no outsider, who is not a descendant of Aaron, should come near to offer incense before the LORD, that he might not become like Korah and his companions, just as the LORD had said to him through Moses. Numbers 16:39-40 (NKJV)
The lesson I learned to day is I need to do my calling well. If my calling is to be a doctor then I should be the best doctor. If it is to be a teacher then I should be best teachers. Otherwise I would be no different then the 250 Levites who were punished by God.