Pesachim 117 - Praise
As we just said , after the second cup of wine at the Seder, all begin to say praise to God, who, having put us in dire straights, later saved us. There are many opinions about who composed those verses and when: David, Moses, the Sages, the Jews at the sea, and so on. There are also ten gradations of praise found there, each introduced with a special word. For example, when the psalms starts with "By David, a song," - this means that first God’s presence rested on David, and then he recited the song. On the other hand, when it starts with "A song by David," - he recited the song, and afterward the Divine presence rested on him.
This tells us an important principle: the Divine presence does not rest on one who is lazy or sad or frivolous, but rather on the one who experiences a serious joy. This is illustrated in the story of Elisha, who asked for music, and when a musician played, " God’s hand rested on Elisha ."
Art: Joyous Woman by Ferdinand Hodler