Commentary for Deuteronomy 33:9

האמר לאביו ולאמו לא ראיתיו WHO SAID TO HIS FATHER AND TO HIS MOTHER, I HAVE NOT SEEN HIM — When they sinned in the matter of the golden calf and I said, “Who is on the Lord’s side, let him come to me” (Exodus 32:26), all the sons of Levi gathered themselves unto me, and I ordered them each to kill his mother’s father, he being an ordinary Israelite, or his brother on the mother’s side, or the son of his daughter whose husband was an ordinary Israelite, and thus did they do. — It is impossible to explain the term “his father” literally, and “his brothers” as being those on his father's side, and similarly to understand “his sons” literally, for really all these are Levites, and of the tribe of Levi no one sinned., as it is said, “[And there gathered unto me) all the tribe of Levi” (Sifrei Devarim 350:1, Yoma 66b).

האומר לאביו, during the episode of the golden calf,

האומר…יורו משפטיך ליעקב. "Who says ….they shall teach Your laws to Jacob." We may explain this verse best according to Baba Batra 60 where the Talmud relates that Rabbi Yannai had a tree the branches of which overhung the adjoining street causing inconvenience to the passers-by. He was called upon to expound the law in a similar situation and asked to be given until the morrow before presiding over this litigation. During the intervening night he gave instructions to cut down the branches of his tree which overhung the street so as not to be accused of being himself guilty of an offence which he was supposed to adjudicate. [The Talmud explains that originally Rabbi Yannai had thought that the shade provided by his tree for the passers-by outweighed any damage it could cause to the passers-by who failed to look where they were going. Ed.] The word האומר is an allusion to the kind of judge qualified to sit in judgment of others, i.e. only people who ensure that their own house is in order may judge others. In order to face one's parents and criticise them one must first be free from guilt himself.