«وَإِذَا عَبَّرَ حَبَّرَ»
When he expresses an idea, he makes the expression artful.
ʿAbbara concerns conveying a meaning in words; ḥabbara concerns making the resulting composition polished and pleasing. Their sound pattern is close, but the two actions are distinct.
The ideal author does not choose between communication and beauty. First the meaning must be conveyed; then the phrasing can sharpen its memorability and effect. The elder claims both qualities for the unnamed writer.