Another verse where Abu Tammam goes wrong is the following:
The places where your tribe once stayed are vacant, I attest,
[their traces] worn away like the washa’i‘ of a mantle.
He treats washa’i‘ as if they were the mantle's bordered edges, but this is not the case. In reality, washa’i‘ are a weaver's "shuttles," which carry the coiled thread of the weft between the fibers of the warp. Dhu 'l-Rumma says [correctly]:
[The sands] are played by strenuous winds
like the weaving of a Yemeni whose washa’i‘ weave a mantle.
As for the verse of Kuthayyir,
In summer, the huts of ‘Azza's tribe were wiped away,
whose washī‘ had been renewed in a scrawling pattern [sic].
He uses washī‘ here to mean the stuffing in a gap between two things. But shuttles are for thread... and what Kuthayyir means is that [the sides and ceilings of] the huts had been re-stuffed [with grass]. This mistake is due to his inexperience of the trappings of settled life. When a Bedouin uses the wrong word for something, having never seen it first-hand, it is excusable.
For Abu Tammam, on the other hand, there is no excuse, because he belonged to sedentary civilization, and was hardly ignorant of it. But he grants himself license, [and is flagrant about it,] as you can see in another poem where he describes his own poetic work:
Jest and earnest are combined in the shuttling of its weft,
as are nobility and scurrility with grief and ecstasy.
From The Weigh-in Between the Poetry of Abu Tammam and al-Buhturi by Abu 'l-Qasim al-Amidi