Something is defined as a source in Usul when it serves as a source for new Ahkam (rules). Qiyas is a source because we can extract new Ahkam from it. By extending the original rule to new realities via a shared „Illah, leads to new Ahkam for new realities and hence Qiyas is a source. This is one of the ways we can appreciate the capacity of Islam to apply to all times and places as Ahkam can be deduced for new realities and problems.

Qiyas is always built on the following four pillars:

i. Asl (old matter).

ii. Fari‟ (new matter).

iii. Hukm (rule).

iv. „Illah (effective reason).

For example Allah (swt) said:

“And make ready against them all you can of power including horses to threaten the enemy of Allah.” (TMQ Al-Anfal: 60)

The Hukm given in the verse is that preparation is an obligation. The old matter is horses. The „Illah is to terrify the enemy of Allah. As for the new matter, it is anything that will realise the „Illah of the preparation, which is to terrify the enemy. So these days it would be obligatory to have tanks, fighter planes, and aircraft carries since they terrify the enemy. Not only that, the „Illah obliges the Islamic State prepare in the following areas:

a) The arms development and war industry must be the strongest of its age if it is to fulfill the „Illah of terrifying the enemy.

b) The state cannot depend on others for its sources of power and hence it has to strive to develop its own weapons and armaments.

c) It should have new sophisticated weapons which will strike fear in the hearts of the enemy.

There are specific guidelines and requirements for Qiyas explained in the books of Usul al-Fiqh. One such guideline is that there should be no existing ruling from the Qur‟an, Sunnah and Ijma‟ as-Sahabah for the new case.

Example: Does a woman have to remove the nail polish before performing Wudhu? Some people claim she does not have to remove the nail polish in order to do Wudhu, and they justify it by doing Qiyas on the performance of Masah (wiping over the socks).

Qiyas cannot be performed in this situation because the Ayah regarding Wudhu explicitly orders to wash all parts of the hands, and polish prevents water from reaching the nails. In the case of Masah (wiping over the socks) the text is not presented with an „Illah (legal reason) and cannot be extended to other things. Thus, Qiyas can be practiced in this issue.

Some of the other requirements for Qiyas are that the original ruling has to be from Qur‟an, Sunnah and Ijma‟ as-Sahabah, not from another Qiyas. In addition, the texts of the Qur‟an, Sunnah and Ijma‟ as-Sahabah must contain the justification for the ruling. We cannot use our „Aql (intellect) to come up with the cause („Illah).