Shariat dalillari shariat hukmlarining asosi (usullari) bo'lib, ular din asoslari kabi qat'iy bo'lishadi, shuning uchun zanniy (gumonli) emas. Butun shariatning usullari, ya'ni dinning usullari ham, shariat dalillari bo'lgan ahkomning usullari ham qat'iy bo'lishi shart va ularni zanniy qilish joiz emas, chunki Allohning quyidagi so'zi bor: {Bilmagan narsangga ergashma…} (Isro surasi, 36-oyat) hamda Uning: "Ularning ko'pchiligi faqat gumonga ergashadi; gumon esa haqiqatga qarshi hech narsani foydasiz qila olmaydi. Albatta, Alloh ularning qilayotgan ishlarini yaxshi biladi" (Yunus surasi, 36-oyat). Ulamolarning aksariyati usulul-ahkom qat'iy (qat'iyah) bo'lishi kerakligini zikr qilganlar. Hofiz, mujtahid Abu Ishoq Ibrohim ibn Muso al-Laxmiy al-G'arnotiy, al-Shotibiy nomi bilan mashhur, o'zining "al-Muvofaqot" kitobida shunday degan: "Albatta, fiqh usullari qat'iydir, zanniy emas, va buning dalili shuki, ular shariatning kulliyotlariga (umumiy qoidalariga) qaytariladi, va bunday narsa qat'iy bo'ladi." Shuningdek, u aytadi: "Agar zanniy narsa shariatning kulliyotlariga bog'lansa, u shariatning asosiga (aqidaga) ham bog'lanishi mumkin bo'lib qoladi, chunki aqida birinchi kulliyotdir, bu esa joiz emas." Yana u aytadi: "Agar zanniyni fiqhning asosi qilish joiz bo'lsa, uni dinning asosi qilish ham joiz bo'lib qoladi, holbuki buning joiz emasligi ittifoqiy masaladir. Fiqh usullari shariatga qanday aloqador bo'lsa, usuli din ham shunday aloqadordir, bu yerda ham shunday." U yana aytadi: "Ba'zi olimlar aytganlar: shariatning asosini zanniy bilan isbotlash yo'li yo'q, chunki bu qonunchilikdir, biz zanniy bilan ibodat qilmaymiz, faqat tarmoqlarda (furuda) bundan mustasno." Va aytadi: "Asos esa albatta qat'iy bo'lishi kerak, chunki agar u zanniy bo'lsa, ixtilof bo'lish ehtimoli paydo bo'ladi va bunday narsa dinda asos bo'la olmaydi."

The adillah of the shari'ah are the basis (usoul) of the shari'ahi verdicts, they are decisive similarly like the usoul of the religion (deen), so they are not indecisive (dthanniah). The usoul of the whole shari'ah whether they are the usoul of the deen or the usoul of the ahkaam which are the shari'ah evidences are inevitable to be decisive, and they are not allowed to be indecisive for the saying of Allah Ta’ala: {And pursue not that which you have no knowledge…) 36 Surat Al-Israa’, and His saying: But most of them follow nothing but conjecture; truly conjecture can be of no avail against Truth. Verily Allah is well aware of all that they do) 36 Surat Younos. The masses of the scholars had mentioned that usoul al ahkaam must be decisive (qat’iyah), Al-Haafidth Al-Mujtahid Abu Ishaaq Ibraaheem Ibn Mussa Al-Lakhmy Al-Ghornaaty known by Al-Shaatiby said in his book Al-Mowaafaqaat: “verily the usoul of the fiqh of the deen are decisive, not indecisive, and the evidence on that is, because they are referred to the totalities of the shari'ah, and that which is as such; is decisive” and he said: “If the indecisive is related to the totalities of the shari’ah, then it is possible to be related to basis of shari’ah (The Aqeedah), because it is the first totality, and that is not allowed”, and he said: “If it is allowed to make the indecisive one of the basis of the fiqh, then it becomes allowed to make it basis of the deen, and it is unanimously not like that, and so is the case here, because usoul al-fiqh are of the same relation to the shari’ah like usoul al-deen”, and he also said: “ Some scholars said: there is no way to prove the basis of the shari’ah by the indecisive, because it is a legislation, and we don’t worship by the indecisive except in the branshes”, and he said: “ The basis however, must be decisive; because if it is indecisive; it would be a possibility of disparity and such thing could not be a basis in the deen”.

Imom Jamoliddin Abd al-Rahim al-Asnaviy o‘zining "Nihoyat al-sul" kitobida buyruq fe’lining dalolati haqida gapirganda, bu borada noaniq dalil e’tiborga olinmasligini aytadi. U shunday deydi: "Ahod (yakka rivoyat qilingan) xabarga kelsak, u botildir; chunki yakka rivoyat noaniq dalilni foydali qiladi, Shoriy esa noaniqlikka faqat amaliy masalalar, ya’ni furu’larda ruxsat bergan, ilm masalalari, masalan, usul al-dinning asosida esa ruxsat bermagan, shuningdek, usul al-fiqhning asosida ham ruxsat bermagan; bu haqda al-Anboriy (al-Burhon kitobining sharhlovchisi) ulamolardan hammasi birgalikda rivoyat qilgan." Biroq Qur’oni karimning oyatlari usullarda noaniqlikka amal qilishni qat’iy man etgani va noaniqlikka ergashgan kishini qoralagani aniq. Bu matnlar shariatning asoslari, umuman olganda, ular usul al-dinmi yoki usul al-ahkommi, qat’iy bo‘lishi kerakligini va noaniq bo‘lishi joiz emasligini ko‘rsatadi. Shuning uchun fiqh asoslarida hech qanday noaniqlik yo‘q, chunki bu haqda aniq taqiq bor, balki usul al-fiqhning barcha asoslari qat’iydir. Shunga ko‘ra, shar’iy dalil sifatida qabul qilinishi uchun unga qat’iy dalil o‘rnatilishi kerak va agar unga qat’iy dalil o‘rnatilmasa, u shar’iy dalil hisoblanmaydi. Haqiqiyligi qat’iy dalil bilan isbotlangan dalillar to‘rttadir: Qur’oni karim, Sunnat, sahobalar ijmo’i va illati shar’iy matn bilan bayon qilingan qiyos. Bu to‘rttasidan boshqasi shar’iy dalil hisoblanmaydi, chunki ular uchun qat’iy dalil yo‘q. Shunga ko‘ra, shar’iy hukmlarning asoslari, ya’ni shariat dalillari, aynan shu to‘rttasi bilan cheklanadi va boshqasi e’tiborga olinmaydi.

Imaam Jamaal Al-Deen Abd Al Raheem Al-Asnawy, in his book, Nihayat Al-Sou’l At the discussion of the denotation of the (imperative verb, do) with respect to that, the indecisive daleel is not considered he said: “And as for the Aahaad (individually narrated); it is invalid (baatil); because the individual narration avail the indecisive, and The Legislator allowed the indecisive in the branches only, which are the practical issues, without the knowledge issues like the basis of usoul al-deen, and also the basis of usoul al-fiqh, as Al-Anbaary (the explainer of Al-Borhaan book) transmitted from the scholars all together”. However, the verses of The Qur’aan are explicit about forbidding the indecisive in the usoul, and blaming whoever follows the indecisive, and these texts dictate that the basis (usoul) of the shari’ah in general whether they are usoul al-deen or usoul al-ahkaam (verdicts usoul); must be decisive, and it is not valid to be indecisive. Therefore there is nothing indecisive in the basis of the fiqh at all, because of the explicit forbiddance about that, but all basis of usoul al-fiqh are decisive. Accordingly, for the shari'ahi daleel to be considered as evidence; decisive evidence must be established for it, and unless decisive evidence is established for it; it is not considered as shari'ahi daleel. The adillah which the decisive evidence stood up to prove their validity are four only, they are: The Qur’aan, The Sunnah, The Consensus of The Sahaabah and The Qiyaas which has illah denoted by shari'ahi text, and anything other than these four is not considered as shari'ahi daleel, because there is no decisive evidence for them. Accordingly, the bases of the shari'ahi verdicts, i.e. the shari’ah evidences are confined to these four and nothing else is considered.