What does the Torah add the words "be'Etzem ha'Yom ha'Zeh"?
Rashi (citing the Sifri): Because Yisrael were saying that they would never allow Moshe to be taken from them. 1 So Hakadosh-Baruch-Hu said 'I will take him away in the middle of the day; See if you can stop Me!' 2
Targum Yonasan: To hint that he would die on that very day - the seventh of Adar - the same day on which he was born. 3
Kli Yakar: Death is called sunset. Moshe at his death still had his full strength; it is as if he was in the middle of his days, like the sun be'Itzumu (at its greatest strength, at noon).