Charles Ellicott Commentary Leviticus 10:20

"And when Moses heard [that], it was well-pleasing in his sight." — Leviticus 10:20 (ASV)

And ... he was content. —He acknowledged Aaron’s plea to be just, and that he himself had spoken hastily. This is a remarkable instance of Moses’ humility and the human side of his nature as a lawgiver. (See also Numbers 32:6 and following).

Therefore, Jewish tradition since time immemorial ascribes the mistake to Moses, and not to Aaron. The paraphrase of this verse in the Palestine Chaldee Version, which embodies the ancient opinions, is very instructive. It is as follows: “And when Moses heard it, he approved of this explanation. Then he sent a herald through the whole camp of Israel, saying, ‘It is I from whom the law had been hidden, and my brother Aaron reminded me of it.’”