"Neither a borrower nor a lender be"
From Shakespeare's Hamlet.
The principle of avoiding debt, and avoiding giving loan guarantees, is found in the Proverbs.
Proverbs 22:7
The rich ruleth over the poor, and the borrower is servant to the lender.
Proverbs 11:15
He that is surety for a stranger shall smart for it: and he that hateth suretiship is sure.
Proverbs 17:18
A man void of understanding striketh hands, and becometh surety in the presence of his friend.
Proverbs 6:1-3
My son, if thou be surety for thy friend, if thou hast stricken thy hand with a stranger, [2] Thou art snared with the words of thy mouth, thou art taken with the words of thy mouth. [3] Do this now, my son, deliver thyself, when thou art come into the hand of thy friend; go, humble thyself, and make sure thy friend.