From this morning’s parshah:
כִּי עַבְדְּךָ עָרַב אֶת-הַנַּעַר, מֵעִם אָבִי לֵאמֹר: אִם-לֹא אֲבִיאֶנּוּ אֵלֶיךָ, וְחָטָאתִי לְאָבִי כָּל-הַיָּמִים.1
For thy servant became surety for the lad unto my father, saying, If I bring him not unto thee, then I shall bear the blame to my father for ever.2
The introduction of a recently published article of mine:
Yehudah’s guarantee of his brother Binyamin’s return to their father Ya’akov is one of the sources the Gemara adduces for the principle that a cosigner (arev) of a loan is responsible for its repayment, and while the Gemara’s discussion of the principle is mostly limited to an actual cosigner, who by his assurance to the lender induces him to lend money and thereby potentially incur a loss should the borrower default, the poskim generalize the doctrine to other situations where someone’s assurance induces another to take some action that can potentially result in loss. This article explores some of the classic cases they discuss, and the parameters of the doctrine they establish.
The article, along with a companion lecture, a compilation of sources, and a lengthy, comprehensive highly technical (Hebrew) article I published a number of years ago on this topic are available at the Internet Archive.