وما لم ينص عليه فهو محمول عادات الناس
Translation: For items whose measure is not specified by text, the prevailing practices of people govern.
When there is no specific textual assignment of a commodity to volume or weight, the recognized commercial custom helps determine its category.
This is not a license for parties to redefine the operative cause at will. It concerns a genuine prevailing measure for commodities whose measure was not fixed in the cited texts. Hanafi commentaries record further disagreement about whether shifting custom can affect even some textually mentioned items.