Rabbi Shimon says that the two brothers and sister; Moses, Aaron and Miriam had supernal level of holiness. They died in different times and places to protect the Israelites from different danger. Miriam died in Kadesh that was between North to South because she was a chariot to Malchut. Malchut is between Right and Left of Zeir Anpin that is North-South. Aaron was a chariot of Chessed and he died in Hor Mount that was on the Right.
Moses died on the mountain of Abarim (Deuteronomy 32:49) that was in the middle that was proper for Moses that represents the Central column, Tiferet (from Da’at down)).
‘Abarim’, ‘עברים’, means ‘passages’ to represent the passages on the right and left of the mountain. As a chariot for the Central Column, Moses was holding both Right and Left columns.
The merits of Tzadikim stand for them in this world and the upper world. Even after their passing, they have great influence on the world below.
When God has a decree on Israel and they have some merit, he calls the Tzadikim and notify them about it. They can cancel the decree and the Holy One Blessed be He shows mercy on the Israelites.
“וְנָחֲךָ יְהוָה תָּמִיד וְהִשְׂבִּיעַ בְּצַחְצָחוֹת נַפְשֶׁךָ וְעַצְמֹתֶיךָ יַחֲלִיץ וְהָיִיתָ כְּגַן רָוֶה וּכְמוֹצָא מַיִם אֲשֶׁר לֹא יְכַזְּבוּ מֵימָיו”
“And YHVH will continually guide you, And satisfy your desire in the purity of your soul, And give strength to your bones; And you will be like a watered garden, And like a spring of water whose waters do not fail.”