...The Scholars of usool have deduced from the Book and the Sunnah many usool (fundamental principles), upon which they have built many rulings; by which they have also benefited themselves and benefited others.
Amongst these usool (fundamental principles):
[1] "Al-yaqeen laa yazoolu bish-shakk [certainty is not invalidated by doubt]."
Under this principle they have entered many ?ibaadaat (acts of worship), mu?aamalaat (social interactions) and huqooq (rights). So whosoever entertains a doubt regarding any of that, should return to the asl of certainty. They also deduce: "al-aslut-tahaarah fee kulli shay [The basis concerning all things is that they are pure]." And: "al-aslul-ibaahah illaa ma dallad-daleelu ?alaa najaasatihi aw tahreemihi [The asl (basic principle) is permissibility of using anything, except when there exists an evidence indicative of its impurity or prohibition]." And: "The asl is freedom from accountability concerning obligations towards the creation, until a proof is established to the contrary." And: "The asl is the continuation of accountability concerning the obligations to the Creator, and to His servants, until there is certain proof of freedom and discharging."
[2] And from them is that: "Al-mashaqah tajlibut-tayseer [difficulty brings about ease]."
Based upon this are all the rukhas (concessions) allowed during a journey, and a lightening of ?Ibaadaat (acts of worship), mu?aamalaat (social transactions), and other matters.
[3] And from it is their saying: "Laa waajib ma?al-?ajaz wa laa muharram ma?ad-daroorah [there is no obligation with inability, nor is there any prohibition with necessity]."...