Music in Islam and why those who deny it is haram are commiting an act of kufer. (The rule in islam "denying something in islam that haram to being halal or something halal to being haram is kufer" it renders one a non beliver.) The qur'an and hadeeth, along with the statements of the companions and salaf confirm the prohibition of music.

Surah Luqmaan:06 'and there are among men those who purchase idle talk (music and poetry) in order to mislead others from Allah's path without knowledge, and who throw ridicule upon it 'Idle talk has been interpreted to mean singing, listening and playing of musical intruments by various scholars and companions including Abdullah Ibn Masood ans Abdullah Ibn Abbas. Masood when questioned about the term Idle Talk replied 'I swear besides whom there is no other God, that it refers to singing (ghinaa).

Contrary to popular belief there are a number of Sahih (Authentic) Hadeeth which clearly point to the fact that music, instruments, singing to the accompaniment of instruments etc. are prohibited by the Shari'ah.

Sahih Bukhari> 'there will be those of my Ummah who will seek to make lawful: fornication, the wearing of silk, wine drinking and the use of musical instruments..' The words, 'seek to make lawful', shows that music is not permissible. Furthermore the prohibition of music is mentioned along with major sins like drinking and fornication.

Ibn Majah, Abu Dawood and Ibn Habban>> 'A people of my Ummah will drink wine, calling it by other than that, it's real name. Merriment will be made for them through the playing of musical instruments and the singing of female singers. Allah will cleave the Earth under them and turn others into Apes and Pigs'

There are Hadeeths by Haakim Al Mustadrak, Musad Ahmad Ibn Hanbal and Majma uz Zawaaid that say 'Two cursed sounds are that of the wind instrument and that of wailing upon the occurrence of adversity'

Bukhari & Muslim both quote 'Remember! To fill a persons stomach with puss is better than to fill it with poems.'

There are those who will argue that the prophet (saw) liked the sound of the Duff (a small hand drum without steel jingles) The beating of the Duff at weddings was not for the purpose of music, it was to announce the wedding.
An Nasee&Tirmidhi>> 'that which distinguishes the allowed marriage from the forbidden is the sound of the duff'

Though the scholars argue that the use of the duff was even only allowed for women.The duff was used by Arabs without rhythm, melody or any trace of immorality.

In the highly regarded book on fiqu and fatawa FATAWA RAHIMIYAH, it states 'Quawwali ,tabla and musical intruments etc. are absolutley prohibited (haram). It is reported in the Musand of Ibn Abi Al-Dinar that the holy prophet (pbuh) said "In the last era a community from this Ummah will be transformed into monkeys and swines" The companions said "oh apostle of Allah! Will they not be believing in the Kalima 'there is no deity but Allah and Mohammed is his apostle'?" the prophet (saw) said "why not?" the companions asked "then what will be the reason for this punishment?" the prophet (saw) replied "they will adopt the profession of singing and music" he also said "It is a sin to hear music, it is a fault to sit at a musical fete and it is infidelity to derive pleasure from it" (Nisab, b.52,p 103, DM&S vol 5 p 306)

The great Imams, Imam Abu Hanifa, Imam Shafi & Imam Malik all declared the playing of and listening to of music Haram.