61 But Nadab and Abihu died when they made an offering before the LORD with unauthorized fire.)

Read Numbers 26:61 Using Other Translations

And Nadab and Abihu died, when they offered strange fire before the LORD.
But Nadab and Abihu died when they offered unauthorized fire before the LORD.
But Nadab and Abihu died when they burned before the LORD the wrong kind of fire, different than he had commanded.