מדרש על סנהדרין 222:8

From here they ruled: (The members of) an ass-caravan or a camel caravan that goes from place to place and rested within it, and they were turned astray with them — If it camped there for thirty days, they are put to death by the sword and their possessions are lost; if less than thirty days, they are put to death by stoning, and their possessions "escape."