What does "Al-Pi Hashem" refer to?
Why does the Torah tell us the day that Aharon died? It does not do so for Moshe!
Elef ha'Magen: Refer to 33:8:151:1. He died in Av, the month in which Yisrael cried for naught, and it was decreed that they cry for future generations. Aharon's death hinted to cessation of Avodah (both Churbanos were on Tish'ah b'Av). The Torah does not tell us the day that Moshe died, for Torah will not cease; it is eternal.
QUESTIONS ON RASHI
Rashi writes that Aharon died through a kiss. What is this?
Moshav Zekenim #1: He put his lips together, and died, i.e. without any pain.
Moshav Zekenim: It was amidst clinging to Hashem and love of Him. Hashem put His Shechinah on him, and he prophesied and died. "Kiss" hints to the way lovers kiss when they depart.