Arthur Conan Doyle's "The Adventure of the Speckled Band"

Back in September last year, I read Arthur Conan Doyle's "The Adventure of the Speckled Band," and Sherlock Holmes' comment that "Violence does, in truth, recoil upon the violent, and the schemer falls into the pit which he digs for another" caught my attention.  It seemed to have Biblical precedent, and a few months later, I ran across a very similar passage in Psalm 7 in the NKJV:  "15 He made a pit and dug it out, and has fallen into the ditch which he made.  16 His trouble shall return upon his own head, and his violent dealing shall come down on his own crown."  The pit imagery is the same as that in Holmes' comment, but "His trouble shall return upon his own head, and his violent dealing shall come down on his own crown" has a more literal analogue in the story, even more than Holmes' "Violence does, in truth, recoil upon the violent."

Near the end, Holmes deduces that Dr. Grimesby Roylott has been letting a snake into his step-daughter's room in an effort to kill her and prevent her upcoming marriage, which would have a devastating financial effect on him.  When Holmes attacks the snake with a cane, it retreats to Roylott's room and kills him instead.  Holmes and Watson enter his room to find that "Round his brow he had a peculiar yellow band, with brownish speckles, which seemed to be bound tightly round his head."  Roylott's "violent dealing" has literally "return[ed] upon his own head" in the form of the snake.

While there's definitely a similarity between the Psalm and the end of Holmes' adventure, I don't know whether this is just a coincidence or whether Conan Doyle created this situation in such a way that Holmes can draw this Biblical parallel.*

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*A couple of Holmes' comments that I stumbled upon indicate that he does believe in God, which in turn suggests a familiarity with the Bible:  at the end of "The Boscombe Valley Mystery," he says, "God help us!  ...  Why does fate play such tricks with poor helpless worms?  I never hear of such a case as this that I do not think of Baxter's words and say, 'There, but for the grace of God, goes Sherlock Holmes'" and in "The Adventure of the Empty House," he says, "Halfway down I slipped, but by the blessing of God I landed, torn and bleeding, upon the path."