In addition to The Accessible Conspectus, I am also finishing up a commentary for Ibn Mulaqqin’s Shāfiʿī fiqh Memorandum. This commentary is tentatively titled The Evident Memorandum. Since people often find the conditions for sales somewhat perplexing, I figured that I would take the opportunity to show some of the evidence and reasoning behind the rulings given in the previous post. The text below is from The Evidence Memorandum. The book includes documentation for all of the hadiths and passages it cites. I have removed them here.
7 Sales And Other Transactions
A sale, linguistically, is exchanging property for property. Ibn al-Rufʿah defined it as exchanging one property that is subject to disposal for another property that that is subject to disposal, with an offer and an acceptance, in a manner that has been permitted for it to be done.
The foundation is Allah Most High saying, “…But Allah has permitted trade and has forbidden interest [ribā]…,” [Q2:275] and similar verses, as well as the well-known verses coming in this chapter, and the consensus of the Ummah.
[Sales are] valid with an offer and acceptance,…
The requirement for the offer and acceptance are out of analogy to marriage. So it is not valid to exchange by just giving the specific price without a verbal offer and acceptance. This [type of exchange] is said to be acceptable in transactions where that is customary. Many scholars preferred this opinion (including al-Nawawī) since there is no authentic text establishing that a verbal phrase is required, thus making it necessary to go back to custom, just like for other phrases.