I think it's a reference to money lenders, who were (or were perceived to be) Jewish. Heirs of rich people would borrow money to support their life styles, money to be paid back (under the terms of a post-obit bond) when they inherited the family fortune. (Or so it works out in novels by Georgette Hayer, Bulwer-Lytton, Disraeli, etc.) The OED has a bunch of citations, including a different Byron one. So on the death of the wealthy ancestor, the once-poor heir would be pestered by the money lenders.