Those who are far away from useless things, do not lean towards acts which do not give any benefit and are men of piety as per the Shariah, for them there are certain rules for Qawwali. As the first Mufti of Jamia Nizamia has said:
1. In the assemblies of these persons, there should be no beardless person when singing.
2. All of them should be only of one gender. In their assemblies, there should be no lovers of this world (Dunya) and no sinner.
3. The singer should sing only for the sake of Allah SWT and should have no desire for money or food.
4. These pious persons should not have gathered there for having food.
5. When they stand up in a state of ecstasy (Wajd), they should get up only when they have lost control (Maghlub ul Haal).
6. They should express only that Wajd, which is true.
For those pious people who fulfill all these conditions, listening to Qawwali is permissible and allowed (jayaz and Mubah).
Those who do not fulfill the above conditions should avoid listening to Qawwali.