Is it permissible for a Muslim to follow the dispensations (rukhus) across the different madhhabs (schools of thought), and what is the original reason for the اختلاف (disagreement) among the imams, and do they differ in the fundamental sources of legislation?

The legal concessions (rukhsas) established by the Qur’an and Sunnah are permissible to follow and adopt, for the Prophet, peace and blessings be upon him, said: "Indeed, Allah loves that His concessions be observed just as He loves that His firm resolutions be observed."

However, following the concessions of jurisprudential schools (madhahib ijthadiyah) without a valid reason is considered an evasion of religious obligations and an impermissible transgression. Ibn Hazm narrated a consensus on this matter. Sulaiman al-Taymi said: "If you were to adopt the concession of every scholar, all evil would gather in you." It was also narrated from Ibn Abd al-Barr that he said: "This is a consensus about which I know of no disagreement."

As for the differences among the imams in matters of subsidiary branches, it is natural. Its cause is their varying understanding of the religious text, and contention regarding the authenticity of the text and its suitability for argumentation. The agreement of the imams is a conclusive proof, and their disagreement is a wide mercy.