What are "ha'Poretim Al Pi ha'Navel"?
Rashi citing Menachem: This is like "u'Feret Karmecha" (Vayikra 19:10). Rashi ? this is correct, for one who sings with an instrument, he cuts his speech very finely. He makes it higher or lower, based on the instrument.
Radak: Ha'Poretim is like Chazal said Prat u'Chlal - pertaining to the individuals and the difference from the Klal. I.e. every step in their songs is based on the lyre. One does not resemble another in their singing.
Radak #1: Poretim refer to the strings on the lyre; each is according to its note.
Radak #2: Poretim is like Perutah. Each gives a Perutah to the one who plays.
Radak citing Targum Yonasan: He plays based on the lyre.
Why does it say "k'David Chashvu Lahem Kli Shir"?
Rashi: They considered their instruments like those of David. David's were for Shamayim ? theirs are for pleasure!
Radak: Like David, who knew how to play all instruments. They think that they know like him. This entire matter discusses that they engaged only in pleasures, and did not remember Hashem.
