As for rational consideration, it supports this in several ways. The first is that contracts and conditions belong to ordinary customary acts, for which the default rule is non-prohibition. This presumption of non-prohibition therefore remains in force until there is evidence of prohibition, just as the default rule concerning things is that they are not prohibited. Allah’s words, “He has explained in detail to you what He has forbidden you” [al-An‘ām: 119] [al-An‘ām: 119], apply generally to both things and acts. If they are not prohibited, they are not invalid, [for invalidity arises only from prohibition; and if they are not invalid,] they are valid.

Furthermore, revealed law contains nothing to indicate that contracts and conditions as a class are prohibited unless the permissibility of each particular one has been specifically established. We shall explain, Allah willing, the meaning of Aisha’s hadith and show that the absence of evidence of prohibition is itself evidence of non-prohibition. Thus, both the rational presumption of continuity and the absence of any revealed proof establish non-prohibition. Entering into such contracts and conditions is therefore either lawful or belongs to the category of matters left unrestricted, like things that have not been prohibited.

Most of the proofs used to establish that the default rule concerning things is non-prohibition—general revealed texts, sound analogies, the rational presumption of continuity, and the absence of a ruling when evidence for it is absent—also establish that contracts and the conditions incorporated into them are not prohibited. This holds whether such matters are termed lawful or left unrestricted, according to the well-known disagreement among our fellow jurists and others. Among the practices for which Allah censures the disbelievers in the Quran for imposing prohibitions without revealed authority, some involved prohibiting things and others involved prohibiting acts. For example, they used to forbid a pilgrim in ihram who was not an Ahmasī (a member of the Hums) from wearing his own garments and circumambulating in them, ordering him instead to strip naked unless an Ahmasī lent him his garment. They also forbade him from entering beneath a roof. Similarly, the Ansar used to forbid a man from having vaginal intercourse with his wife when she was [bent forward with her face down], and they also forbade