Yazidism organises revelation around performance. The qewl is the highest of its verse genres, a sacred hymn of authoritative standing, distinguished from the beyt and other songs of the tradition, and its custody belongs to a defined class: the qewwals, drawn from particular lineages in the twin villages of Bashiqa and Bahzani on the Nineveh plain, who learn the hymns, their melodies and their instruments, the shibab flute and the def frame drum, through years of training. Performance is liturgy, not concert.
Qewls sound at the great autumn Feast of the Assembly at Lalish, at the spring new year, in the rites surrounding death, where particular hymns accompany the soul's passage, and in the periodic processions that carry the sanjaks, the bronze peacock standards of Tawusi Melek, among the Yazidi districts. The theology the hymns carry is allusive and layered: God's creation of the world beginning from a pearl, the mystery of the Seven Angels to whom the world's governance was entrusted, the exaltation of Tawusi Melek, the Peacock Angel, and the histories of Sheikh Adi and the holy men of Lalish. Reciters and religious dignitaries expound them in prose commentary, since the hymns compress more than they explain. Knowledge of the full corpus has always been unevenly distributed, held by specialists rather than by the community at large, which made the tradition resilient against outsiders and vulnerable to the loss of its carriers.