Deuteronômio 31:2

וילך משה וגו' ... אנכי היום AND MOSES WENT ... I AM [HUNDRED AND TWENTY YEARS OLD] THIS DAY — Today my days and my years become full: for on this day (the seventh of Adar; cf. Rashi on Deuteronomy 1:3) I was born and on this day I must die (Sotah 13b). לא אוכל עוד לצאת ולבוא I CAN NO LONGER GO OUT AND COME IN — One might think that this was because his physical strength failed him! Scripture, however, states (Deuteronomy 34:7) “His eye was not dim nor his natural force abated!” What then is the meaning of לא אוכל? It means: “I am not permitted” (cf. Rashi on Deuteronomy 12:17 and Deuteronomy 24:4), because the power (leadership) is being taken from me and given to Joshua. — Another explanation of לצאת ולבוא is: I can no more take the lead in the matter of the Law; this teaches us that the traditions and the well-springs of wisdom were stopped up for him (cf. Sotah 13b). וה' אמר אלי — This (according to the previous comment) is the explanation of לא אוכל עוד לצאת ולבוא: I can no more go out and come in because (ו = because) the Lord has said unto Me, [Thou shalt not pass over this Jordan].

And he said to them, I am a hundred and twenty years old this day; I can no more go out and come in: also the Lord has said to me, Thou shalt not go over this Yarden.

וַיֹּ֣אמֶר אֲלֵהֶ֗ם בֶּן־מֵאָה֩ וְעֶשְׂרִ֨ים שָׁנָ֤ה אָנֹכִי֙ הַיּ֔וֹם לֹא־אוּכַ֥ל ע֖וֹד לָצֵ֣את וְלָב֑וֹא וַֽיהֹוָה֙ אָמַ֣ר אֵלַ֔י לֹ֥א תַעֲבֹ֖ר אֶת־הַיַּרְדֵּ֥ן הַזֶּֽה׃