Green’s Dictionary of Slang

any form of bond or oath that has been sworn in return for money.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Kerry security, bond, pledge, oath and keep the money.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue [as cit. 1785].