Adillah za shariah ndizo msingi (usuul) wa hukumu za shariah, na ni za hakika (qat'iyyah) kama ilivyo usuul za dini (deen), kwa hiyo si za dhana (dhanniyyah). Usuul za shariah yote, iwe ni usuul za dini au usuul za ahkaam, ambazo ni dalili za shariah, lazima ziwe za hakika, na haziruhusiwi kuwa za dhana kwa kauli ya Allah Ta'ala: {Wala usifuate yale usiyo na ujuzi nayo…} (Suratul Israa, 36), na kauli Yake: "Lakini wengi wao hawafuati lolote ila dhana; hakika dhana haiwezi kufaa chochote mbele ya Haki. Hakika Allah anajua vyema wanayoyafanya." (Suratu Yunus, 36). Wanazuoni wengi wametaja kwamba usuul al-ahkaam lazima ziwe za hakika (qat'iyyah). Al-Haafidh al-Mujtahid Abu Ishaaq Ibraaheem bin Muusa al-Lakhmiy al-Ghornaatiy, anayejulikana kama al-Shaatibiy, alisema katika kitabu chake al-Muwaafaqaat: "Hakika usuul za fiqh za dini ni za hakika, si za dhana, na ushahidi wa hilo ni kwamba zinarejelewa kwenye jumla za shariah, na kilicho hivyo ni cha hakika." Pia alisema: "Ikiwa dhana inahusiana na jumla za shariah, basi inawezekana kuhusishwa na msingi wa shariah (al-'Aqiidah), kwa kuwa hiyo ndiyo jumla ya kwanza, na hilo haliruhusiwi." Na alisema: "Ikiwa inaruhusiwa kufanya dhana kuwa msingi wa fiqh, basi itaruhusiwa kuifanya msingi wa dini, na jambo hilo kwa makubaliano halikubaliki, na ndivyo ilivyo hapa, kwa kuwa usuul al-fiqh zina uhusiano na shariah sawa na uhusiano wa usuul al-dini." Alisema pia: "Baadhi ya wanazuoni walisema: hakuna njia ya kuthibitisha msingi wa shariah kwa dhana, kwa kuwa hiyo ni sheria, nasi hatufanyi ibada kwa dhana isipokuwa katika matawi." Na alisema: "Msingi hata hivyo lazima uwe wa hakika; kwa sababu ukiwa wa dhana, kutakuwa na uwezekano wa kutofautiana, na jambo kama hilo haliwezi kuwa msingi katika dini."

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”.

Imam Jamaal Al-Deen Abd Al Raheem Al-Asnawy, katika kitabu chake, Nihayat Al-Sou’l. Katika mjadala kuhusu dalala ya (kitenzi cha amri, fanya) kuhusiana na hilo, dalili isiyo na uhakika haizingatiwi, alisema: "Na kuhusu Aahaad (habari za mtu mmoja mmoja); ni batili; kwa sababu habari ya mtu mmoja huleta dhana isiyo na uhakika, na Mwenye Kutoa Sheria (Ash-Shaari') aliruhusu dhana isiyo na uhakika katika matawi peke yake, ambayo ni masuala ya vitendo, bila masuala ya elimu kama msingi wa usuli al-deen, na pia msingi wa usuli al-fiqh, kama Al-Anbaary (mfafanuzi wa kitabu cha Al-Borhaan) alivyopokea kutoka kwa wanazuoni wote kwa pamoja." Hata hivyo, aya za Qur'aan ziko wazi kuhusu kukataza dhana isiyo na uhakika katika usuli, na kuwalaumu wale wanaofuata dhana isiyo na uhakika, na maandiko haya yanaonyesha kwamba msingi (usuli) wa shari'ah kwa ujumla, iwe ni usuli al-deen au usuli al-ahkaam (usuli wa hukumu), lazima uwe wa hakika, na si sahihi kuwa usio na uhakika. Kwa hiyo hakuna kitu kisicho na uhakika katika msingi wa fiqh kabisa, kwa sababu ya katazo lililo wazi kuhusu hilo, bali misingi yote ya usuli al-fiqh ni ya hakika. Kwa hivyo, ili dalili ya kishari'ah izingatiwe kuwa ushahidi, ushahidi wa hakika lazima uthibitishwe kwa ajili yake, na isipothibitishwa kwake ushahidi wa hakika, haihesabiwi kuwa dalili ya kishari'ah. Dalili ambazo ushahidi wa hakika umesimama kuthibitisha uhalali wake ni nne tu, nazo ni: Qur'aan, Sunnah, Ijmaa' ya Maswahaba, na Qiyaas yenye illa iliyodhihirishwa na maandiko ya kishari'ah, na chochote kingine isipokuwa nne hizi hakihesabiwi kuwa dalili ya kishari'ah, kwa sababu hakuna ushahidi wa hakika kwa ajili yake. Kwa hiyo, misingi ya hukumu za kishari'ah, yaani ushahidi wa shari'ah, imehusishwa na hizi nne peke yake, na hakuna kingine kinachozingatiwa.

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.