«وليس قرب قبر حرب قبر»
There is no grave near the grave of Ḥarb.
The nearby expressions qurb, qabr, Ḥarb, qabr repeat related consonant sequences. Each item is manageable separately, but rapid transitions within the whole sentence become cumbersome.
The example demonstrates that a word does not have to be rare or intrinsically awkward for its use in a particular arrangement to impair the eloquence of the complete utterance.