For the source text click/tap here: Bava Metzia 81
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§ The mishna teaches: One who lent to another based on collateral is a paid bailee for the collateral. The Gemara comments: Let us say that the mishna is not in accordance withthe opinion of Rabbi Eliezer. As it is taught in a baraita: With regard to one who lends to another based on collateral and the collateral was lost, the lender take an oath that he was not negligent in his safeguarding, and then he may take his money that he lent him.
We explore the history of collateral loans.