לֹ֥א בַשָּׁמַ֖יִם הִ֑וא לֵאמֹ֗ר מִ֣י יַעֲלֶה־לָּ֤נוּ הַשָּׁמַ֙יְמָה֙ וְיִקָּחֶ֣הָ לָּ֔נוּ וְיַשְׁמִעֵ֥נוּ אֹתָ֖הּ וְנַעֲשֶֽׂנָּה׃
하늘에 있는 것이 아니니 네가 이르기를 누가 우리를 위하여 하늘에 올라가서 그 명령을 우리에게로 가지고 와서 우리에게 들려 행하게 할꼬 할 것이 아니요
Rashi on Deuteronomy
לא בשמים הוא IT IS NOT IN HEAVEN — for were it in heaven it would still be your duty to go up after it and to learn it (Eruvin 55a).
Sforno on Deuteronomy
לא בשמים היא, in order to repent you do not need to turn to a prophet who represents heaven,
Rabbeinu Bahya
לא בשמים היא, “it is not in heaven;” it is possible that the reason Moses makes this point is because prior to bringing the Torah to the people it had indeed resided in heaven, and we have quoted arguments offered by the angels opposing its descent to earth. The word היא which we might have considered as redundant, is a reference to the highest level of חכמה, the emanation wisdom, which does indeed reside in heaven.