invalidate the contract.
14 – Concerning his words, “conditions that are not found in the Book of Allah,” Ibn al-Qayyim explains that “the Book of Allah” here cannot possibly mean the Quran itself, for the majority of valid conditions are not mentioned explicitly in the Quran but are known from the Sunnah. Rather, “the Book of Allah” refers to His ruling, for the expression is applied both to His revealed speech and to the legal judgement He conveyed through the tongue of His Messenger ﷺ. It is therefore clear that any condition which is not in accord with the ruling of Allah stands in opposition to it and is therefore void. The correct position is to annul every condition that contravenes the judgement of Allah, and to uphold every condition that Allah has neither prohibited nor forbidden.
15 – Walāʾ (the bond of clientage) is an agnatic tie that arises from the beneficence of the emancipator toward the freed person. Hence the Prophet ﷺ said, as recorded by al-Ḥākim (7990) and Ibn Ḥibbān (4950): “Walāʾ is a flesh-bond like the bond of blood-kin; it is not to be sold or given away.” By virtue of that bond the emancipator inherits, and his male agnatic heirs inherit after him, as will be explained in its proper chapter, Allah willing.
16 – Many scholars were puzzled by the Prophet’s permitting ʿĀʾishah to purchase Barīrah while the sellers stipulated that walāʾ should remain theirs, a condition that is manifestly invalid. The best explanation is that the sellers were fully aware that the stipulation was void yet chose to proceed; the Prophet ﷺ therefore decided to treat them contrary to their intent. He allowed them to continue with the condition for a while, then publicly declared its invalidity and non-enforceability. He became angry and reproved them for trifling with the ordinances of Allah, but he couched his admonition in general terms so that the deterrent would apply to them and to others alike—his accustomed method in such situations.
Difference of opinion among the scholars:
The jurists disagreed: Is the default ruling concerning contracts and conditions prohibition unless the Law explicitly permits them, or is the default permissibility and validity, with only those that the Law designates as forbidden and void being unlawful? Shaykh al-Islām stated that the first view is that of the Ẓāhirīs and of many of the foundational authorities