WÂJIB – واجب
Literally: Necessary. Incumbent. Compulsory. Bounden duty. Right. Proper. Necessary to be followed.
As a term of fiqh: An obligatory act, with failure to perform it being sinful. There is no difference between fardh and wâjib in practising. It is an obligation to perform them and failure to perform them is sinful.
As a term of ‘Ilm al-Kalâm: Allah’s (jalla jalâluhu) existence is a necessity and impossible not to be existent.
“There are degrees in the Sunnah as-Saniyyah: some are wâjib; these may not be abandoned. This sort is described in detail in the Illustrious Sharî’ah. They are muhkamât and can in no way be changed. Another sort is nawâfil, and these are of two sorts:
One sort is the Sunnah as-Saniyyah which concerns ‘ibâdah. They too are described in the books of the Sharî’ah, and to change them is bid’ah. The other sort is called âdâb, and are mentioned in the books of the Prophet's biography (siyar). Opposition to them cannot be called bid’ah, but it is an opposition of a sort to the Prophet's âdâb and means not benefiting from their nûr and true adab. This sort is to follow Ar-Rasûl Al-Akram ‘Alayhissalâtu Wassalâm’s actions concerning general custom, habitual actions and fıtrî acts, which are known through tawâtur. For example, there are numerous Sunnah as-Saniyyah showing the âdâb of speaking, and explaining the principles of the âdâb of eating, drinking, and sleeping, and concerning social relations. The Sunnahs of this sort are called âdâb. One who follows this âdâb transforms his habitual actions into ‘ibâdah and receives significant faydh from the âdâb. Practising the smallest aspect of such âdâb recalls Ar-Rasûl Al-Akram ‘Alayhissalâtu Wassalâm, and imparts a nûr to the heart.
The most important among the Sunnah as-Saniyyah are the Sunnahs which are the symbols of Islam and connected with the shaâ’er. Shaâ’er is an ‘ubûdiyyah concerning the community which are general rights of a sort. As the whole community benefits from one person performing them, so the whole community is responsible in their abandonement. There can be no riyâ in the performance of shaâ’er of this sort, and they should be proclaimed. Even if they are of the nawâfil sort, they are still more important than personal fardhs.” The Eleventh Flash- Sixth Subtle Point