For the first time, the 700-year-old tradition of singing 'qawwalis' is under attack at the famed Sufi shrine of Hazrat Nizamuddin in the Indian capital.
Qawwalis are a key attraction at the shrine, and every Thursday thousands - Muslims as well as non-Muslims - crowd the dargah, located in the midst of narrow lanes of the Nizamuddin area to listen to the artistes.
Now, a cold war has erupted within the Muslim community: is qawwali Islamic or un-Islamic?
Those who preach the orthodox strand of Islam, known as Tablighs, are making it clear that singing of and listening to qawwalis - a Sufi tradition - should stop at the 14th century shrine.
The Tablighs believe that praying at shrines amounts to idol worship. They are objecting to the tradition of singing qawwalis, which are Sufi hymns, at the Nizamuddin dargah and at the nearby Hazrat Inayat Khan dargah.
The Tablighs have already succeeded in stopping the qawwalis in some of the smaller Sufi shrines in the city. Naturally, there is despair at the Nizamuddin shrines.
The Tablighs and the Sufis have a different understanding of Islam. While the Tablighs frown upon what they say are deviations from the basic fundamentals of Islam, Sufism - essentially a sub-continental phenomenon - is widely viewed as the tolerant face of Islam.
Many Sufi saints enjoy the near status of god. Muslims and also many non-Muslims pray at their shrines by lighting incense and following rituals that is not accepted by mainstream Islam.
Nearly seven centuries after the Nizamuddin shrine was built, the Tablighs have come up with a modern structure nearby housing their international headquarters.
Ironically, the devotees heading for the shrine in the Nizamuddin area in south Delhi have to now go past this structure, known as the 'markaz'.
Although thousands of devotees, cutting across class and religious divides continue to visit the shrine each day, the influence of the Tablighs is visibly growing in the Nizamuddin area.
Zubair, whose eating joint is situated bang in front of the markaz, says: "These people tell devotees not to go to the dargah. They think this amounts to idol worship.
"We are here because of Hazratji. He wants us to be here. He provides for us, but we do not worship him. We only pray at his shrine and our wishes come true."
For the convenience of devotees, toilets have been built at the entrance of the shrine. The keeper of the toilet is Raju, a Hindu. Like many from his community, he too has full faith in Hazrat Nizamuddin: "Hazratji takes care of us."
Meraj Ahmed, the head qawwal whose ancestors have been singing at the shrine for centuries, confesses that Tablighs are against the singing.
"I know people from the markaz don't want us to sing at the dargah," he said.
Ahmed and his team sing not only Sufi compositions at the shrine but also bhajans (Hindu hymns). "Qawwalis are a mix of many poetic styles, including Persian and Arabic, and are based on the classical structure of 'tala' and 'raga'," Ahmed explained.
The head of the Nizamuddin shrine, Peer Syed Ahmed Nizami, says: "Tablighs have for long been preaching that going to shrines is un-Islamic. But they have intensified their campaign in recent times."
Asked if the Tablighs ever approached him directly, he said: "They can propagate against us but they cannot stop us."