1Now Nadab and Abihu, the sons of Aaron, each took his censer and put fire in itand laid incense on it and offered unauthorized fire before the LORD, which he had not commanded them.
What is told here takes place on the same day as the initial priestly offering recorded in chapter 9.
1 Now Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it and laid incense on it and offered unauthorized fire before the LORD, which he had not commanded them.