200 FAQ On Muslims Belief by Hafiz Ibn Ahmed Al Hakami

A--- There are two divisions:

First: Adopting methods of worship other than those prescribed by Allah the Almighty. For instance, the ignorant Sufis use musical instruments accompanied with dance, clapping, and singing resembling those in whose regard Allah the Almighty says: {Their Salat (prayer) at the House (of Allah, i.e. the Ka'bah at Mecca) was nothing but whistling and clapping of hands). (Al-Anfal, 35)

Second: Adopting as a method of worship that is originally lawful, but it is done in other than its proper place, time, or manner. For instance, unveiling one's head is permitted while practicing Ihram, but if one who is not wearing Ihram does it while performing Prayers, Fasting or other acts of worship with the intention of drawing near to Allah thereof, this is deemed an unlawful Innovation. Besides, performing supererogatory prayers in the forbidden times, and fasting the first day of the two 'Ids.