Ana ɗaukar wani abu a matsayin tushe a cikin Usul idan yana zama tushen samun sabbin hukunce-hukunce (Ahkam). Qiyas tushe ne domin ana iya fitar da sabbin hukunce-hukunce daga gare shi. Ta hanyar mika asalin hukunci zuwa sabbin al'amura ta hanyar illa guda da ake rabawa, sai a samu sabbin hukunce-hukunce don sabbin al'amura da matsaloli, don haka Qiyas tushe ne. Wannan na daga cikin hanyoyin da za mu fahimci iyawar Musulunci na dacewa da kowane lokaci da kowane wuri, domin ana iya fitar da hukunce-hukunce ga sabbin al'amura da matsaloli.

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.

Ana gina Qiyas koyaushe a kan ginshiƙai huɗu kamar haka:

Qiyas is always built on the following four pillars:

i. Asali (abin da ya gabata).

i. Asl (old matter).

II. Fari‟ (sabon abu).

ii. Fari‟ (new matter).

iii. Hukunci (hukunci na shari'a).

iii. Hukm (rule).

iv. 'Illah (dalilin hukunci mai tasiri).

iv. „Illah (effective reason).

Misali, Allah (SWT) ya ce:

For example Allah (swt) said:

"Kuma ku shirya musu duk abin da za ku iya na karfi, har da dawakai don tsoratar da abokan gābar Allah."

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

Hukuncin da aya ta bayar shi ne cewa shirya kayan yaƙi wajibi ne. Abin da ya tsufa a wannan al'amari shi ne dawakai. Dalilin hukuncin (al-'Illah) shi ne tsoratar da abokin gābar Allah. Dangane da sabon abu kuwa, duk abin da zai cika dalilin shirya kayan yaƙin, wato tsoratar da maƙiyi, shi ne abin da ya shiga hukuncin. Saboda haka a wannan zamani zai zama wajibi a mallaki tankuna, jiragen yaƙi, da jiragen ruwa masu ɗauke da jirage, domin suna tsoratar da maƙiyi. Ba wannan kaɗai ba, dalilin hukuncin yana wajabta wa Daular Musulunci ta shirya a fannoni masu zuwa:

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) Masana'antar ci gaban makamai da yaƙi dole ne ta kasance mafi ƙarfi a zamaninta idan za ta cika manufar "Illah" ta tsoratar da abokan gaba.

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) Gwamnati ba za ta iya dogaro da wasu don samun tushen ƙarfinta ba, saboda haka dole ne ta yi ƙoƙari wajen ƙera makamanta da kayan yaƙinta da kanta.

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) Ya kamata ya mallaki sabbin makamai masu inganci waɗanda za su sa tsoro a zukatan abokan gaba.

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

Akwai takamaiman ka'idoji da sharuɗɗa na Qiyas da aka bayyana a littattafan Usul al-Fiqh. Ɗaya daga cikinsu shi ne cewa bai kamata a sami hukunci da ya riga ya wanzu daga Alƙur'ani, Sunnah da Ijma'in Sahabbai ga sabon lamarin ba.

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.

Misali: Shin mace na bukatar cire goge-farce kafin ta yi Alwala? Wasu mutane suna ikirarin cewa ba ta bukatar cire goge-farce don yin Alwala, kuma suna tabbatar da hakan ta hanyar yin Qiyas a kan yin Masah (shafa a kan safa).

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).

Ba za a iya yin qiyas a wannan yanayi ba saboda aya game da alwala ta umurci a wanke dukkan sassan hannu a fili, kuma goge-goge yana hana ruwa isa ga farce. Amma a batun Masah (shafa kan safa) nassi bai zo da 'illah (dalilin shari'a) ba, don haka ba za a iya mikar da shi zuwa wasu abubuwa ba. Saboda haka, ana iya yin qiyas a wannan batu.

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.

Daga cikin sauran sharuɗɗan Qiyas akwai cewa hukuncin asali dole ne ya kasance daga Alƙur'ani, Sunnah da Ijma'ul Sahabah, ba daga wani Qiyas ba. Haka kuma, nassan Alƙur'ani, Sunnah da Ijma'ul Sahabah dole ne su ƙunshi hujjar hukuncin. Ba za mu yi amfani da hankalinmu ('Aql) wajen ƙirƙirar dalilin hukunci ('Illah) ba.

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).