What is "Kol ha'Sirim Tachas ha'Sir"?
Rav Sadya Gaon: It is thorns under a cooking pot 1 .
Rashi: A copper pot is inverted over burning thorns, and they knock into it. Metzudas David - it is not an organized sound, as opposed to the sound of a musical instrument.
Ibn Ezra: Sirim is like "Hineni Sach Es Darkech ba'Sirim" (Hoshe'a 2:8); he will put thorns on the path. Sir is like "b'Shivtenu Al Sir ha'Basar" (Shemos 16:3). The verse mentions Sirim and Sir for a clear expression, just like "Rochevim Al Sheloshim Ayarim u'Sheloshim Ayarim Lahem" (Shoftim 10:4; the former are donkeys, and the latter are cities).
What is the comparison to the sound of thorns?
Rashi citing Koheles Rabah: There is not a big noise from burning wood. Thorns make a great noise, to announce 'also we are wood!' So Kesilim increase words, to say 'we are among the esteemed.'
Ibn Ezra: The song of Kesilim, and their laughter and Simchah, has no reason or significance. It is mere voice and screaming, like the sound of thorns.
Ri Kara: Burning thorns make a big noise, and extinguish immediately. So song of Kesilim - when he hears it, he enjoys it, and when he turns to leave, he finds his household hungry and lacking all good. What caused this? He turned his heart to hear the song of Kesilim and neglect his work.
Seforno: Thorns are lost in the sound of the fire. They ruin the pot, even though they cook the meat inside 1 . So the Kesil ruins himself and the one who listens to him via wasting time, even though it delights him for a short time.
Metzudas David: Just like the thorns do not make an organized sound, so the Kesil's song is not straight; matters of light-headedness are mixed in.
I.e. if the pot is from a weak substance, the thorns puncture it. (PF)
Why does it say "Gam Zeh Hevel"?
Rashi 1 : Hashem put Kesilim in the world in order to weary and antagonize people.
Refer to 7:6:2:2.
Rashbam: A fire of thorns is not an important fire, like of other wood. A Kesil says many words without reason, rebuke or Chachmah. Therefore, one should distance from Kesilim and laughter of their words.
Ri Kara: Both the sound of thorns and the laughter of Kesilim, both of them are Hevel.
Rid: Also to hear a Chacham's rebuke and grow wise is Hevel! Refer to 7:7:2:4.
Seforno: This Simchah for a short time, its purpose is not important.
Metzudas David: Even though there is some good in the song - it gladdens the heart and removes worry - it is Hevel, for matters of light-headedness are mixed in.
According to the Magihah in Toras Chayim.
