Proverbs 26:9 New English Translation

⁹Like^[a] a thorn^[b] has gone up into the hand of a drunkard,
so^[c] a proverb has gone up^[d] into the mouth of a fool.^[e]

Proverbs 26:9 tn The line does not start with the comparative preposition כ (kaf) “like,” but the proverb clearly invites comparison between the two lines.
Proverbs 26:9 sn The picture is one of seizing a thornbush and having the thorn pierce the hand (עָלָה בְיַד־, ʿalah v^eyad). A drunk does not know how to handle a thornbush because he cannot control his movements and so gets hurt (W. McKane, Proverbs [OTL], 599). C. H. Toy suggests that this rather means a half-crazy drunken man brandishing a stick (Proverbs [ICC], 475). In this regard cf. NLT “a thornbush brandished by a drunkard.”
Proverbs 26:9 tn Because of the analogy within the verse, indicated in translation by supplying “like,” the conjunction vav has been translated “so.”
Proverbs 26:9 tn The verb has been supplied from the first colon because of the convention of ellipsis and double duty (omitting a word in one line which is understood to apply from another line).
Proverbs 26:9 sn A fool can read or speak a proverb but will be intellectually and spiritually unable to handle it; he will misapply it or misuse it in some way. In doing so he will reveal more of his folly. It is painful to hear fools try to use proverbs.

New English Translation (NET)