CHILDREN OF AHARON AND OF MOSHE
במדבר פרק ג א תֶּא הָֹֹוהְי רֶּּבִּּד םֹויְּב הֶּ שמּו ןֹרֲהַא תֹדְלֹוּת הֶּ לֵאְו-מש ֶּה בְּהַר סִּינָֹי:
“And these are the children of Aharon and Moshe on the day that HaShem spoke to Moshe on Mount Sinai”
The verse starts with Aharon and Moshe, but only lists the sons of Aharon.
Sanhedrin 19b
Derives that since Moshe taught Torah to Aharon's sons it is as if they were his children. This learning began at Har Sinai as mentioned in this verse.
Rashbam At the time of Har Sinai, all four children of Aharon learned from Moshe.
Ramban
At Har Sinai, the Cohanim were already selected to serve HaShem and, thus, all their names are mentioned; the Leviim were not selected until later.
Chasam Sofer
In parshas Ki Sisa when Moshe set up his tent outside the camp all who were interested in hearing the word of HaShem would make the trek. Moshe transmitted the Torah during this period of time only to those who were "mevakshei Torah." At Har Sinai Moshe went back and to HaShem, he did not attend to his personal needs. At that time the bnei Aharon did come to hear his words and his own sons did not. It was at that point that the sons of Aharon had the status of Moshe's sons and his sons did not have this. Thus this verse mentions Har Sinai since at that time Moshe was not involved with his personal family matters.
Birkei Yoseif
One who teaches his friend’s son Torah is considered as if he were his father. This lesson is strategically placed by Moshe and Aharon. We might mistakenly believe that this concept is true only when the biological father does not teach his son Torah. However, Aharon taught his sons Torah, as related in the Gemara Eiruvin 54b, and nevertheless, Moshe is still considered their father.
Rabbeinu Z'charioh
Moshe's children are not mentioned. This is because Moshe's children did not experience the exodus from Egypt, nor the splitting of Yam Suf.
Ari z"l
The teacher pours his spirit into his student in the same manner as a father to a son, and the connection between a teacher and student is even stronger than with a parent. Because of this input the teacher has a portion in all the mitzvos his student does.
Medrosh Rabbah
Why Aharon is mentioned here ahead of Moshe? When Moshe and Aharon were involved with the census they also asked for the family lineage. People chided Aharon, "Before you ask for our lineage look at the lineage of the offspring of your son Eleazor, who married the daughter of Puti'eil." Standing up for Aharon's honor, HaShem mentioned him ahead of Moshe in the chapter of the Levites offspring.
Yalkut Yehudoh
Why didn't the people likewise chide Moshe, who did the exact same thing as Eleazor, taking Tziporah the daughter of Puti'eil as his wife? Elozor had the opportunity to marry a woman who was born to the Jewish nation, while Moshe was in Midyon for many years and had no such luxury.
Nodah BiYehudah
One who teaches his friend's child Torah, is as if he gave birth to that child. This is to be taken literally, and one can fulfill the mitzvah of "pru u'rvu" by teaching another's child, like Moshe did.
Rabbi Shlomo Kruger
They are considered Moshe's children because he saved their lives with his supplication at the time of the death of Nadov and Avihu (see Rashi on VaYikra 10:12 that this is the intention of Moshe in the words "Va'espallel gam b'ad Aharon" (Devarim 9,20).
Sfas Emes
Why are only the sons of Aharon mentioned? Moshe taught all the Bnei Yisroel Torah. The rest of the Bnei Yisroel later fell from their exalted level through the sin of the golden calf, but the children of Aharon remained righteous.
