Many of Nusrat Fateh Ali Khan’s greatest qawwal performances feature lyrics about ‘Ali ibn Abi Talib, probably originally deriving from the song, “Man Kuntu Mawla,” attributed to Amir Khusrow (d. 1325). Bulleh Shah (d. 1757) is said to have modified this song to create the popular qawwal “Mast Qalandar” in honor of the Sufi saint…