Deuteronómio 33:9 Comentario: Rashi, Chizkuni, Ibn Ezra & Kli Yakar

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).

כי שמרו אמרתיך, “for the Levites observed Your commandments not to defile the sanctity of the Tabernacle/Temple.” (Leviticus 21,12) None of the Levites committed the error of worshipping the golden calf, and they were prepared to execute family members whom they found doing so. (Sifri and Rashi)

Who says … [singular] “The tribe” is the subject of the verb. The reference is to, e.g., Samuel, who came to train in the House of God as soon as he was weaned [I Samuel 1: 22].

כי שמרו אמרתך BECAUSE THEY KEPT THY WORD, viz., Thou shalt have no other gods,