ḤEREM HA-IKKUL (Heb. חֵרֶם הָעִקּוּל, "ban on confiscation"), a prohibition against a person retaining an article entrusted to him as a bailee even though he has a subsequent claim against its owner. Because of the dangers of medieval travel, and the consequent lack of security and the fact that Jewish property consisted mainly of cash and movables, there was frequent need for a bailee. This custom, which became generally accepted law, was designed to protect the commerce which was developing as a result of the rise of towns.
Finkelstein, Middle Ages.
"Ḥerem Ha-Ikkul." Encyclopaedia Judaica. . Encyclopedia.com. (August 21, 2018). http://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/herem-ha-ikkul
"Ḥerem Ha-Ikkul." Encyclopaedia Judaica. . Retrieved August 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/herem-ha-ikkul