What this does in a room is the interesting part. The doctrine gets stated once, plainly, and is then abandoned for pure sound, and the sound takes up the long stretch of singing that follows. Nobody is being taught anything after the first line. Everything past it is a gathering finding out what it feels like to sing together.
That first line is a hadith, a reported saying of the Prophet, associated with an occasion at a place called Ghadir Khumm. Whoever's master I am, Ali is his master. Nothing else in the piece is Arabic, and nothing else in it is doctrine.
The sentence sits at the centre of a long disagreement in Islam about succession, and it is central to Shia belief. What matters for the qawwali tradition, which comes down largely through Sunni Chishti Sufis, is something next door to that: Ali is taken as the head of the chain through which spiritual authority passes from master to disciple. Singing this first is a way of naming where the lineage starts before anything else is allowed to begin.
Then the tarana. Da-ra-dil, ta-na-na-na, ya-la-li. Not words in any language, and not meant to be. Tarana is an entire vocal form built out of syllables chosen for how they sit in the mouth and against the rhythm, and its invention is traditionally credited to Khusrau. Whether or not that credit is historically exact, the pairing is what the piece runs on: the most loaded sentence available, and then sound with nothing whatsoever inside it.
Nusrat Fateh Ali Khan's recording is long, because the tarana is where the improvisation lives. The Sabri Brothers sing it closer to how it actually goes at a gathering.
