Aqsaam Al-waajib (the Categories Of The Obligation)
The Waajib is divided or categorised in accordance to different considerations. As such, there is a division in respect to its performance (Adaa’), another in respect to its evaluation (Taqdeer), a third in respect to its designation and a fourth in respect to the one who has been charged with it (Mukallaf).
The categories of the Waajib in consideration of its time of performance or undertaking
Waajib Mutlaq and Waajib Muqayyad (The unrestricted obligation and the restricted obligation):
1 – Al-Waajib Al-Mutlaq (unrestricted obligation):
This is what the Shaari’ (Legislator) has requested to be done without restricting it to a specific time and an example of this type is the Qadaa’ of Ramadhaan for the one who did not fast due to a Shar’iy ‘Udhr (excuse/reason) like sickness or travelling. That is because he can make Qadaa’ for it when he wishes without it being restricted to a specified year. This is the opinion of some of the Fuqahaa’ in this issue including the Hanafiyah. Others however have stipulated that it is a condition for the person to make up (Qadaa’) for what he missed before the coming of the Ramadhaan that follows the Ramadhaan in which he didn’t fast, if the Mukallaf is capable of doing that (i.e. within a year).
Other examples include the Kaffaaraat (expiations) and unrestricted vows (Nudhoor). So whoever breaks one’s oath or vow, without being restricted to a specific time, can undertake the required expiation (Kaffaarah) directly after his breaking and undertake his vow immediately if he wishes to or he can delay it until a time of his choosing.