In “I deposited my needs in a barren valley,” the speaker presents requests to a person or source from which no benefit came. The phrase “valley without cultivation” thus functions beyond a geographic description: it stands for an unfruitful object of hope.
Recognition of the Quranic words establishes the incorporation, while the new relation between a barren valley and unmet needs creates the figurative image.
Iqtibās may coincide with another rhetorical technique, but the grounds for identifying each should be stated separately.