The balance (mizan) and the standards of weight and measure

Mizan comes from weighing a thing; the word is also used for the standard weights of stone or iron and for the instrument used to weigh. ¹

Measure (kayl) is the vessel and the act of measuring. Balance and measure are the root of the fixed quantities of the law and the most used instruments of measure. The mithqal and the ratl are standards by which goods are weighed. ^{1 2}

All Muslims agree that cheating in weight or measure is forbidden. The Qur'an repeatedly forbids it, orders full measure and weight, threatens those who cheat, and treats any shortfall as corruption on earth. The hadith says: whoever cheats us is not of us. ^{2 4}

The rule is that the standard for weighed and measured goods is the usage known in Makka and Madina in the Prophet's time, citing the hadith of Ibn Umar: the measure is the measure of the people of Madina and the weight is the weight of the people of Makka. The Hanafis hold that what the law names as weighed (gold, silver) is always weighed, and what it names as measured (wheat, barley, dates, salt) is always measured; other goods follow custom, and Abu Yusuf takes custom in all cases. The Malikis measure what the law shows was measured and weigh what was weighed, and rely on custom where no text applies. ^{2 3}

The Shafi'is hold that the usage of Makka and Madina governs; what was weighed then is always weighed, and what was measured then is always measured; unknown goods follow the usage of the Hijaz and then of the place of sale. The Hanbalis hold that measure follows Madina's usage and weight follows Makka's in the Prophet's time, and goods with no such usage follow the custom of their place. ^{3 4}

The law sets no fixed punishment for cheating in this world, so it falls under discretionary punishment (ta'zir), as the judge sees fit, even though it is a grave sin. ⁴