Mizmor Shir Lyom HaShabbos

It says in the Kisvei ha’Ari z”l that singing melodies is mainly on Shabbos because on Shabbos, the worlds are elevated to a higher level. And the elevation of a soul is via song and melody.

==== Sefer Hamamorim 5672, Perek 403 [Parshas V’eirah 5775]

On Shabbos, the worlds are elevated. The neshamos are elevated out of Gehinnom. The neshamos in Gan Eden Hatachton and in Gan Eden Ha’elyon are elevated and are at a higher level, which brings the neshamos to a higher level of pleasure. Therefore, on Shabbos, when we eat and experience oneg Shabbos with our bodies, we also sing melodies to bring pleasure, through song, to our neshomos that are elevated.

UFARATZTA RABBI SHALOM BER MUNITZ