Rabbi Levi Yitzchak interprets “and all the sons of God shouted for joy” according to the Zohar, in the sense of breaking. However, the Rebbe points out that the plain meaning of the verse is that the angels (“the sons of God”) cannot sing their song above until the sons of Israel (who are likened to the stars) sing from below. Note that the value of the entire verse is 3 times chashmal (chashmal), a clear hint to those angels who are silent [chash] to hear the song of Israel and only then speak [mal].
As mentioned, this expresses the idea that although the words of the Jewish people below need to be elevated by the angels, their song is above the song of the angels, and the angels need it. We can go further and say that the reason the angels shout in the morning—shouting as a type of shattering—is because when they hear the song of Israel, they realize they cannot sing like them, their hearts break within them, and out of a broken heart, they sing their own song.
An analogy can be brought from human affairs. Sometimes people witness an extraordinary person and how he praises God. Their hearts break upon recognizing their own lesser abilities, in comparison. By experiencing broken heartedness, they come to elevate their own praise of God. Now, the angels, even after shattering when they hear Israel’s song, remain at a level lower than the song of the souls. However, among humans, sometimes, the song of a person who sings from a broken heart is dearer than the song of a person whose praise sounds and appears loftier, for there is nothing more whole than a broken heart.
