Daily Zohar # 3158 – Vayelech – Moses will sing his “song”
There are two forms for a song, “שיר” for male aspect, Zeir Anpin and “שירה” for female aspect, Malchut. All the prophets that were much below Moses were saying “שיר”. Moses was saying “שירה”. It was more proper for Moses to say “שיר” to represent his connection to Zeir Anpin and Rabbi Aba explains that the secret behind this is that Moses didn’t say it to himself but for all Israel.
Rabbi Shimon says that this is not the explanation and add that Moses was on a level that was above all. He went up from below and the prophets came down from above.
The direction of holiness is always up, never down. Moses starts with “The Song” “שירה” in Malchut, praising the queen, climbing to higher levels of holiness for unification with the King. The “Song” “שיר” of the other prophets were from Zeir Anpin going down to Malchut. For that reason, Moses was above all and his “Song” “שירה” would be sung in the future (Exodus 15:1) “אָז יָשִׁיר מֹשֶׁה וּבְנֵי יִשְׂרָאֵל אֶת הַשִּׁירָה הַזֹּאת לַיהוָה” “Then Moses and the Israelites will sing the song (שירה) to YHVH:”
Deuteronomy 31:21 “ וְעָנְתָה הַשִּׁירָה הַזֹּאת לְפָנָיו לְעֵד” “the song (שירה) will testify before them as a witness”