Bede, on Prov 26:9

“As if a thorn should grow in the hand of a drunkard: so is a parable in the mouth of fools.”

“As if a thorn should spring forth in the hand of a drunkard, etc. A thorn springs forth in the hand of a drunkard when, in his works, who serves carnal seductions, the pricks of sins arise. To these rightly is compared a parable which the foolish propose, for although the foolish may know how to utter wise words, they do not know how to avoid the pricks of sins by which they either lacerate themselves or their neighbor. For often indeed, the imprudent one, in saying good things, either secretly seeks his own praise from men or the censure of others.”

Imported from an open dataset — not yet checked against the printed edition.