...which would probably be out of character for Harry -- how likely is it that an eleven-year-old with WASP-sounding parents would spontaneously think of a line from a Jewish ritual? -- but, oh well, know your audience.

Unless he has some of Voldemort's knowledge stored up in that dark side of his? He's traveled pretty far and he's interested in the sorts of things that would lead him to read up on both the social technologies of religions and the cultures of the Muggle superpowers, so he'd be more likely than Harry to get it.

But it's probably just a throwaway reference.