Normally accepted sources on the etymologies of English words make no such claims. The word has typical English-Germanic roots lull[en] + bye. Upon what basis is this supposed Hebrew etymology based? Why have the professors and other linguistic experts who produce the etymologies in dictionaries like the American Heritage and Webster ones not substantiated such a claim?
Do you really want to trust the version of this word's origins by "Jeannie Musick" who also writes on "The Vampire Chronicle TV Series" and “How to Raise a Pet Vampire” over experts who spend their careers studying this word's etymology?