On speech (Proverbs 10:13–14)

בְּשִׂפְתֵי נָבֹון תִּמָּצֵא חָכְמָה וְשֵׁבֶט לְגֵו חֲסַר־לֵב׃
חֲכָמִים יִצְפְּנוּ־דָעַת וּפִי־אֱוִיל מְחִתָּה קְרֹבָה׃

b’-sif-tay na-VON ti-ma-TSAY choch-MA v’-SHAY-vet l’-GAY cha-sar-LAYV
cha-cha-MEEM yits-p’-nu-DA-at u-fi-e-VEEL m’-chi-TA q’-ro-VA

On the lips of the discerning may be found wisdom, and a rod for the back of the one who lacks sense.
The wise will store up knowledge, and the mouth of a fool imminent ruin.

These two proverbs revolve around speech, a theme that is dominant through verse 21 of this chapter. The paired vocabulary חָכְמָה/חֲכָמִים and בְּשִׂפְתֵי/וּפִי also hold the verses together. Verse 13b is a variation on 26:3b, which compares the need of a rod for a fool to similar instruments of guidance for animals.

I am inclined to understand verbal ellipsis in both verses, in which case the contrast consists in part in the ironic reversal of meaning of the verb from the first to the second half of the verse: one may find knowledge on the lips of the understanding (taking the verb as a deontic modal expressing permission and hence invitation to partake of the offered wisdom), and one must find a stick for the back of one lacking sense (a deontic modal interpretation expressing necessity: there is no other way to guide one lacking sense). Similarly, the wise will store of knowledge (understood positively as valuing it and storing it up for future use), and the mouth of the fool stores up imminent destruction (in the sense of building up just desserts for their talk). The ironic reversal of the verbs in one case involves the modal interpretation, in the other the metaphoric understanding of the lexeme “store up.” In both cases, however, if the reversals lend to the “antithetical” contrast of the two halves.