A sequence of endings may repeatedly feature a final ā-sound. The words are not identical, yet the closeness of their terminal sounds can prepare the ear for the next verse while allowing the meanings themselves to develop.
A final alif may belong to a word’s original form or arise through another linguistic structure. Matching sounds do not prove identical morphology or derivation.
Phonology versus morphology: analysis of the verse ending concerns sound and rhetorical placement; morphological analysis concerns the construction of the word. Both can illuminate a passage, but neither should replace the other.