אָדָ֣ם חֲסַר־לֵ֭ב תּוֹקֵ֣עַ כָּ֑ף עֹרֵ֥ב עֲ֝רֻבָּ֗ה לִפְנֵ֥י רֵעֵֽהוּ׃
A man void of understanding is he that striketh hands, And becometh surety in the presence of his neighbour.
Read midrashic interpretation of Proverbs 17:18: and classical rabbinic exegesis.