رَعَيْنَا الْغَيْثَ
“We grazed the rain,” meaning we grazed the vegetation brought forth by rainfall.
The verb “grazed” does not naturally take rain as the animals' food; it takes grass or herbage. The word “rain,” a cause, denotes its effect, the vegetation.
Original sense: rain, the cause.
Intended sense: the grass that grows from rain, its effect.
Relation: causal production.
This is not a similarity between the shape of rain and the shape of vegetation. It is the connection between rainfall and growth.