تعریف و معنای "[offer] {one's} [hen] for sale on a rainy day"

What is the origin of the idiom "offer one's hen for sale on a rainy day" and when to use it?

The idiom "offer one's hen for sale on a rainy day" is likely derived from agricultural or rural settings where hens were valuable assets for providing eggs and sometimes meat. This phrase is used metaphorically to describe making a hasty or impulsive decision to sell something valuable or essential during a difficult or unfavorable time.