The Unusual Origin and Meaning of the Idiom 'Let Sleeping Dogs Lie'

Origin and Meaning of the Idiom 'Let Sleeping Dogs Lie'
'Let Sleeping Dogs Lie' is an idiom which means that it is best to leave things as they are, and not to investigate in anything that will bring forth problems. Who said 'let sleeping dogs lie', and what are its origins?
Sleeping Toddler Boy
"She didn't tell me how to live, and I didn't tell her how to die. We let sleeping dogs lie."
―Jardine Libaire, Here Kitty Kitty: A Novel
Sleep is beauty, and you know the cost of waking up a peacefully sleeping dog! Forget dogs, anyone will start 'barking' if their sleep is disrupted. The multi-headed dog Cerberus, in Roman mythology, who guards the entrance of the underworld, can be put to sleep only with music. In the Harry Potter series, a similar dog is owned by Hagrid, who is named 'Fluffy', and guards the Philosopher's Stone. This fiery dog has to be lulled to sleep with music. If he is awakened, he can simply create havoc!
What Does 'Let Sleeping Dogs Lie' Mean?
It means that it is best not to disturb a situation, and let things remain as they are. Digging out a matter more will invite trouble, and again disrupt settled things. Thus, whenever someone says 'let sleeping dogs lie', they intend to tell that do not probe or question things that have happened. If someone in unaware about something, do not take troubles to wake that person, if ignorance is better.
Origin of the Idiom
The origin is said to be credited to Geoffrey Chaucer, famous for authoring 'The Canterbury Tales'. He had used an akin phrase in his work 'Troilus and Criseyde'. It said: "It is nought good a sleepyng hound to wake." Thus, the phrase warned that it is not good to wake up a sleeping hound, and you'll have to bear the repercussions.
Examples in Sentences
"I don't want to discuss that matter with Amanda anymore. Let sleeping dogs lie. I don't know how she will react if I discuss the issue again."

"If he hasn't said anything about the goof-up you did, do not ask about it ever again. Let sleeping dogs lie."

"Why do you want to know my secrets? Let sleeping dogs lie."

"The citizens will soon forget about the scam you were involved in. Do not worry about the past. Let sleeping dogs lie."

"Our boss should further probe into this matter. He should not let sleeping dogs lie."
Examples in Books and Movies
Books
Let Sleeping Dogs Lie' by Mirjam Pressler (Translated by Erik J. Macki )
Set up in Germany, this is the story of a young woman 'Johanna', in her teens, whose family owns a famous clothing store, a business that was started by her grandfather. While on a school trip to Israel, she comes to know that the store did not belong to her family, and originally belonged to a Jewish family. Shocked to know about this secret, she tries to dig in the truth. After the Nazi regime, the family has decided to let sleeping dogs lie, and they never cared to tell Johanna the truth. On the other hand, Johanna, dealing with her own personal life, has to deal with her grandfather's connection with one of the darkest memories in history.
'Let Sleeping Dogs Lie' by Tami Kidd
Life is perfect for Mara Byrne. She is an accomplished writer, and has a doting husband. However, when her husband dies, she not only has to deal with his loss, but also has to face a dark truth which she comes across. She discovers something that questions whether her 30-year old marriage was indeed a happy one. As she embarks on a journey to unravel the truth, should she dig and probe further, or simply let sleeping dogs lie?
Movie
Sleeping Dogs Lie (1998)
This is a movie loosely based on the real life of Ambrose Small, an owner of theater chains, and a millionaire, who went missing. The case is still unresolved.

Small has sold off his chain of theaters, and after the check was encashed, Small reportedly went missing. His wife, Theresa, has hired a detective Cole Willis. This is a story revolving around Cole, who tries to open a can of ugly worms, also struggling with a growing attraction towards Small's widow.