الرَّاوِيَةُ فِي الْمَزَادَةِ
Employing rāwiyah for the water-container or waterskin carried by an animal.
The term was used for the camel carrying a water-container and was then extended to the vessel itself. The carrier–carried relation supplies the link.
A camel and a water-container do not share the same essential form. Their connection is practical: one transports the other. This shows that a mursal relation need not be physical resemblance; a stable association of bearer and burden can also allow the listener to reach the intended referent.