In the twelfth century al-Shayzari (died circa 1193) wrote a guidebook for muhtasibs (market inspectors) that included advice on ethical weighing practices:

The most accurate scale is that in which the two sides are equal, the pans are balanced and the hole for the attachment on either side of the center of the beam is one third of the thickness of the attachments. This hole should be one third of the way under the peg of the attachment, and two-thirds above it. This allows for the inclination of the scales by taking the tongue of the balance out of the beam of the attachment, and the pan will descend with the slightest weight. As for the scales from Damascus, the position of the hole for the attachment is different from what we have mentioned. Their inclination is allowed by...