John Wesley on Leviticus 10:1

Strange fire - Fire so called, because not taken from the altar, as it ought, but from some common fire. Before the Lord - Upon the altar of incense. Which he commanded not - Not commanding may be here put for forbidding, as it is, Jer 32:35. Now as this was forbidden implicitly; Lev 6:12, especially when God himself made a comment upon that text, and by sending fire from heaven declared of what fire he there spake; so it is more than probable it was forbidden expressly, though that be not here mentioned, nor was it necessary it should be.