Matthew Poole and continuators on Exodus 30:20

20 When they go into the tabernacle of the congregation, they shall wash with water, that they die not : or when they come near to the altar to minister, to burn an offering made by fire unto the LORD.

For though the fault might seem small, yet the command was evident and easie, and therefore the disobedience was worse arguing presumption, rebellion, and contempt. And God is more severe in the matters of his Worship than in other cases.