According to Shi’a beliefs the definition of bid’ah is anything that is introduced to Islam as either being fard, mustahabb, makruh or haram and/or that contradicts the Quran or hadith. Any new good practice that is practiced that does not contradict the Quran or hadith is permissible. However, it is not permissible to say that a new good practice (that does not contradict the Quran or hadith) is obligatory or highly recommended.
For example, one may introduce establishing the tradition of celebrating Muhammad SAW’s birthday through recommended acts such as fasting or giving alms. If someone performs the tradition with the intention of recommendation or obligation, the tradition becomes bid’ah.
The Shia regard some practices that Sunnis deem Islamic (such as Tarawih prayers in congregation and abrogation of Nikah Mut?ah) to be bid’ah. Both of these are considered to be examples of bid’ahs of the second Sunni Caliph Umar ibn Khattab.
As a general rule in Shi’a belief, anything is permissible except whatever is prohibited through divine revelation such as the Quran or hadith
