“During most years, the seventh of Adar — the day of Moshe Rabbeinu’s demise — occurs in close proximity to the reading of Tetzaveh.

Our Sages note that there is an allusion to Moshe’s demise in Tetzaveh, in that this is the only Torah portion (from the time of Moshe’s birth…), in which he is not mentioned by name.

…

The Zohar states that ‘A tzaddik that has passed on is found in all worlds to an [infinitely] greater degree than when he was alive.’

The Alter Rebbe explains that while the tzaddik was alive his life-force was clothed in a physical body, so only a glimmer could be perceived. However, after his demise, this limitation ends and it is possible to receive from his essence.

…. At the time of Moshe’s passing, he ascended to a level far loftier than can be encompassed by a name. Thus at the time of his demise, he is not referred to by name.”