The actions that Rasûlullah ‘sall-Allâhu ’alaihi wa sallam’ did or avoided doing are of two types: The first type of actions consists of the ones which he performed, or avoided doing, as requirements of worship. Every Muslim has to adapt himself to these performances and avoidances. Actions which do not conform with them are bid’ats. The second group are the actions being practised as customs by the people of the cities and the countries in which he lived. He who dislikes them and says that they are unpleasant becomes a disbeliever. But it is not obligatory to practise them. An action not conforming with them is not a bid’at. Doing or not doing them depends on the customs of one’s country and nation. They are categorized as mubâh. They do not have anything to do with the religion. Each country has different customs. In fact, customs of a country may change in the course of time.
Ibni ’Âbidîn ‘rahmatullâhi ta’âlâ ’alaih’, while explaining the sunnats of ablution, writes: “Mashrû’at, namely ’ibâdât, i.e. things which Muslims were commanded to practise, are of four categories: fard, wâjib, sunnat and nâfila. Plain commandments by Allâhu ta’âlâ are called fard. Allâhu ta’âlâ’s commandments that are not as clear as a fard, but are inferred through deduction are called wâjib. Those acts of worship that are neither fard nor wâjîb but which Rasûlullah himself advised or practised are called sunnat. If he performed them steadily and omitted them rarely, and if he did not say anything to those who omitted them, they are called sunnat-i hudâ or sunnat-i muakkada. They are the shi’âr (symptoms) of the Islamic religion. [That is, they are peculiar to this religion; they don’t exist in other religions.] When he saw someone omit a wâjib, he used to dissuade him from omitting it. If he himself omitted it from time to time, it is called sunnat-i ghayri muakkada. It is makrûh to omit a sunnat-i muakkada. It is a venial sin. Allâhu ta’âlâ promised to give thawâbs for all acts of worship. But, being rewarded for a certain act of worship requires intending for it. To intend is to obey the commandments and to remember the fact that the worship is being done to attain the ridâ (grace) of Allâhu ta’âlâ. To perform these three categories of worship in their proper times is called adâ. [Not to perform them in their proper times, but to perform them after their proper times are over is called qadâ. To perform them again upon one’s own wish after adâ or qadâ is called nâfila worship.] It is more blessed to perform fards and wajîbs as nâfila than performing sunnat-i muakkadas. Acts which Rasûlullah ‘sall-Allâhu ’alaihi wa sallam’ performed continuously not as ’ibâdat (worship) but as ’âdat (habit) are called sunnat-i zawâid. His style of attirement, his sitting and standing and his beginning from the right hand side while doing good things are in this category. Those who practise them are also rewarded. It is not necessary to intend to get a reward for them. If they are intended, then they become acts of worship. Their blessing increases. It is not makrûh to omit the sunnat-i zawâid and the nâfila worships.” Nevertheless, following Rasûlullah ‘sall Allâhu ’alaihi wa sallam’ also in acts pertaining to his habits supplies one with many advantages and causes much happiness in this world and in the next.
 Bid’at means an act, a belief, a behaviour that is practised or held as if it were an Islamic commandment, while in actual fact it has nothing to do with Islam; or something that is avoided as if it were something prohibited by Islam, although it is not the case. Bid’ats are worse than any other sinful act, since they involve a slander against the Islamic religion.