The Book of Sales
Part One – The Types of Unrestricted Sales
Discussion of sales is confined to five main points:
- Identifying their various kinds;
- Identifying the conditions of validity for each kind;
- Identifying the conditions that render a sale invalid;
- Determining the rulings that apply to valid sales; and
- Determining the rulings that apply to invalid sales.
Accordingly, we shall first set out the kinds of unrestricted sales, then—one by one—the conditions of invalidity and validity, the rulings of valid sales, and the rulings of invalid sales.
Because some causes of validity and invalidity are common to all (or most) forms of sale while others are particular, and because the same distinction applies to the rulings that follow from validity and invalidity, sound methodological procedure requires us to begin with what is shared among these four categories—namely, the general causes of invalidity, the general causes of validity, the general rulings of validity, and the general rulings of invalidity for all sales. After that, we will address what is specific to each individual type of sale.
Thus, the book is systematically divided into six parts:
• Part One: the types of unrestricted sales;
• Part Two: the general causes of invalidity found in all—or at least most—unrestricted sales, for these are better known than the causes of validity;
• Part Three: the general causes of validity in unrestricted sales;
• Part Four: the rulings common to all (or most) valid sales;
• Part Five: the shared rulings of invalid sales, should they occur; and
• Part Six: a type-by-type treatment of sales, detailing for each its particular rules of validity, invalidity, and legal consequences.
Part One
Every transaction concluded between two parties must fall into one of three categories:
- a specific asset exchanged for another specific asset;
- a specific asset exchanged for something owed in liability;
- a liability exchanged for another liability.
Each of these three categories is either deferred (nasīʾa) or immediate (nājiz); moreover, each may be immediate on both sides or immediate on one side and deferred on the other. Hence the total number of possible sales comes to nine.
A transaction that is deferred on both sides is unanimously impermissible, whether the exchange concerns specific assets or liabilities, because it constitutes the forbidden practice of “a debt for a debt.”